Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 08/25/13


AREA FORECAST DISCUSSION
NWS PHOENIX AZ
440 PM MST SAT AUG 24 2013 .UPDATE...AVIATION DISCUSSION. && .SYNOPSIS... A STORMY PERIOD IS ANTICIPATED THIS WEEKEND ACROSS THE REGION WITH BELOW NORMAL TEMPERATURES. HEAVY RAIN AND LOCALIZED FLOODING MAY OCCUR...ESPECIALLY ACROSS SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA. PRECIPITATION CHANCES DECREASE BY EARLY NEXT WEEK...AND INCREASED MOISTURE WILL CONTINUE THROUGH THE REMAINDER OF THE WEEK...ALONG WITH NEAR NORMAL TEMPERATURES. && .DISCUSSION... WET AND UNSETTLED WEATHER SCENARIO DEVELOPING THIS AFTERNOON PRETTY MUCH AS EXPECTED...AS MOISTURE FROM TROPICAL SYSTEM IVO CONTINUES TO SHED TO THE NORTH AND INTO ARIZONA AND SE CALIFORNIA. BEST MLCAPE/SURFACE BASED CAPE VALUES ARE LOCATED ACROSS SERN CA AND SWRN AZ. PWAT VALUES ARE UP...WITH PHOENIX REPORTING 1.6 INCHES ON THE MORNING RAOB. SURFACE DEWPOINTS AT 2 PM RANGED FROM THE MID 5OS TO MID 60S OVER THE CENTRAL AZ DESERTS...TO THE MID 60S TO LOW 70S OVER PORTIONS OF IMPERIAL COUNTY. STRONG THUNDERSTORMS HAVE BEEN DEVELOPING THIS AFTERNOON WEST OF THE LOWER CO RIVER VALLEY WHERE INSTABILITY IS GREATEST...AND THEY HAVE PRODUCED VERY HEAVY RAINFALL. RADAR INDICATED OVER 4 INCHES OF RAIN FELL WEST OF THE SALTON SEA DURING THE EARLY AFTERNOON. STRONG CONVECTION CAN BE EXPECTED FOR THE REST OF THE AFTERNOON AND INTO THE EVENING HOURS OVER OUR WESTERN DESERTS. MLCAPE VALUES ARE MUCH LOWER OVER SOUTH CENTRAL AZ...MOSTLY LESS THAN 600 J/KG...SO LESS CONVECTION IS EXPECTED. HOWEVER THERE HAS BEEN QUITE A BIT OF SUNSHINE SOUTH AND EAST OF PHOENIX THIS MORNING AND EARLY AFTERNOON AND STORMS WILL LIKELY START TO GENERATE AND MOVE NORTH INTO OUR AREA LATER THIS AFTERNOON AND INTO THE EVENING HOURS. THUS...WE WILL STILL CALL FOR NEARLY 50 PERCENT CHANCE OF THUNDERSTORMS TONIGHT OVER OUR EASTERN ZONES. OTHERWISE...FORECASTS APPEAR ON TRACK AS MOISTURE FROM DECAYING IVO WILL SPREAD INTO THE CWA LATER TONIGHT...WITH PWAT VALUES MAXING SUNDAY INTO SUNDAY NIGHT...IN AREAS WEST OF MARICOPA COUNTY. POPS WILL REMAIN ELEVATED THRU SUNDAY NIGHT...MOSTLY IN THE 60 TO 80 PERCENT BALLPARK. LESS INSTABILITY EXPECTED SUNDAY/SUNDAY NIGHT SO STORMS WILL BE LESS SEVERE BUT THE THREAT FOR HEAVY RAIN WILL BE INCREASED DUE TO PWAT VALUES THAT WILL CLIMB WELL ABOVE 2 INCHES. FLASH FLOOD WATCH WILL CONTINUE FOR ALL ZONES WEST OF ZONE 23 STARTING AT 11 PM TONIGHT AND CONTINUING THRU 11 PM SUNDAY NIGHT. LITTLE CHANGE MADE BEYOND SUNDAY NIGHT...AS MOST OF THE EFFORTS TODAY HAVE BEEN CHASING ONGOING FLOODING AND SEVERE WEATHER EPISODES. FOLLOWING DISCUSSION IS A MORE DETAILED ANALYSIS FROM THE MID SHIFT. PREVIOUS DISCUSSION...A BATCH OF SHOWERS AND THUNDERSTORMS HAVE DEVELOPED OVER THE METRO AREA EARLY THIS MORNING. LATEST RUC IDENTIFIES A PERTURBATION MOVING THROUGH THE SOUTH-CENTRAL ARIZONA DESERTS WHICH MIGHT ACCOUNT FOR THIS. THERE WAS A GRAVITY WAVE THAT MOVED THROUGH BUT THAT WAS AT LEAST A FEW HOURS AGO. THE RUC SHOWS THE PERTURBATION SHIFTING NORTH AFTER 12Z AND THUS STORM ACTIVITY OVER MARICOPA COUNTY SHOULD WIND DOWN SHORTLY AFTER SUNRISE...ALREADY QUIET ELSEWHERE IN THE FORECAST AREA. LARGER SCALE FLOW FEATURES OF NOTE INCLUDE THE EVER-PRESENT TROUGH CENTERED NEAR THE WEST COAST...A LARGE ANTICYCLONE/RIDGE CENTERED OVER THE PLAINS...AN INVERTED TROUGH CENTERED NEAR THE CHIHUAHUA/TEXAS BORDER...AND TROPICAL STORM IVO CENTERED WEST OF CABO SAN LUCAS. THE MODELS HAVE DIFFERING SOLUTIONS ON HOW THE FLOW FEATURES MENTIONED ABOVE WILL UNFOLD...PARTICULARLY THE INVERTED TROUGH AND THE BROADER CYCLONIC CIRCULATION ASSOCIATED WITH IVO. FOR INSTANCE...THE GFS CONTINUES TO TRACK THE IVO ASSOCIATED CIRCULATION TO THE NORTH FASTER THAN ECWMF AND ESPECIALLY NAM. BY THAT SAME TOKEN...THE WAVE ALSO DISSIPATES FASTER. THIS HAS IMPLICATIONS FOR TIMING OF POPS/PRECIP. THERE ARE ALSO DIFFERENCES ON THE UPPER LEVEL DIVERGENCE GENERATED BY THE APPROACHING WAVE WHICH ALSO IMPACTS MODEL PRECIP FORECASTS. THOUGH THE NAM IS SLOWER WITH THE IVO CIRCULATION...IT BRINGS IN A SMALLER WAVE LATER TODAY WHICH MIGHT BE REMNANTS OF THE INVERTED TROUGH AND/OR A CONVECTIVELY GENERATED FEATURE FROM SOUTHERN SONORA. THE NAM THUS PRODUCES A BATCH OF DYNAMICAL FORCING SOONER THAN THE GFS AND ECWMF. THEY ALL SHOW A MAJOR INFLUX OF MOISTURE. INTERESTINGLY...THERE ARE SOME SIMILARITIES IN THE SPATIAL DISTRIBUTION OF THE QPF...INCLUDING LOCAL WRF AND NMM6KM. MAINLY...FROM TONIGHT THROUGH SUNDAY NIGHT THERE IS A HIGH QPF SWATH OVER WESTERN MARICOPA COUNTY AND SOUTHWEST ARIZONA. AND A LESSER SWATH OVER THE HIGHER TERRAIN OF SOUTH-CENTRAL ARIZONA. IN BETWEEN IS A LOWER QPF SWATH...INCLUDING THE PHOENIX METRO AREA. HOWEVER...THERE IS A GREAT DEAL OF VARIABILITY FOR SOUTHEAST CALIFORNIA. THE GFS HAS ITS HEAVIEST SWATH...FOR OUR FORECAST AREA...OVER EASTERN RIVERSIDE AND IMPERIAL COUNTIES. MADE NUMEROUS ADJUSTMENTS TO THE QPF AND POP GRIDS. MODIFIED THE FLASH FLOOD WATCH TO START IT 6 HOURS EARLIER AND TO EXTEND IT EASTWARD OVER WESTERN MARICOPA COUNTY. IT SHOULD BE NOTED THAT WE WILL NOT HAVE A TROPICAL STORM THAT BODILY MOVES INTO THE DESERT SOUTHWEST. RATHER...TROPICAL MOISTURE WILL BE PUSHED NORTHWARD INTO THE REGION AND THERE WILL BE FLOW FEATURES AIDING THE PRECIPITATION PRODUCTION. ALSO...WHILE THE WATCH DOES NOT START UNTIL 06Z...THERE WILL LIKELY BE SOME POTENT THUNDERSTORMS DEVELOPING WITHIN OUR AREA PRIOR TO THAT. THE GFS...NAM...AND SREF ALL HAVE CAPE VALUES WELL IN EXCESS OF 1000 J/KG...MAINLY OVER SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA. PRIOR TO THE ARRIVAL OF BROADER SCALE LIFT...ANTICIPATE STORMS BEING MORE SCATTERED IN NATURE AS OPPOSED TO WIDESPREAD RAIN. WITH HIGH CAPE VALUES...THERE WILL BE SEVERE POTENTIAL LATE THIS AFTERNOON AND EVENING. THEREAFTER...ANTICIPATE DECREASING CAPE BUT MORE WIDESPREAD SHOWERS WITH ISOLATED THUNDERSTORMS. WITH THE CLOUDS AND RAIN COOLED AIR AROUND...SUNDAY TEMPS WILL BE WELL BELOW NORMAL. EXTENDED PERIOD...UPPER LEVEL SUPPORT WANES SLIGHTLY ON MONDAY AND CONSEQUENTLY I THINK THERE SHOULD BE AN OVERALL DECREASE IN STORM COVERAGE MONDAY/MONDAY NIGHT. THE FORECAST FOR TUESDAY THROUGH NEXT FRIDAY WILL CONSIST OF HIGHER THAN NORMAL POPS AND LOWER THAN NORMAL TEMPS GIVEN SUBSTANTIALLY HIGHER THAN NORMAL MOISTURE VALUES. THE GFS AND EUROPEAN MODELS BOTH ADVERTISE A COUPLE OF EASTERLY WAVES NEXT WEEK...ALTHOUGH EACH MODEL SUGGESTS A DIFFERENT DAY /WEDNESDAY PER GFS...TUESDAY FOR ECMWF/. WITH SUCH HIGH PWATS IN PLACE...TUESDAY AND/OR WEDNESDAY COULD BE VERY ACTIVE IF ONE OF THESE TROUGHS ACTUALLY COME TO PASS AS ADVERTISED. THIS WILL ALSO NEED TO BE LOOKED INTO FURTHER AS THE EVENT GETS CLOSER. && .AVIATION... SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA AND KSDL... THROUGH 06Z SUN...LIGHT VRBL WINDS. SCT-BKN CLOUDS 10-15 THSD MSL. 11Z SUN THROUGH 23Z SUN...INCREASING CLDS BCMG 8-10 THSD BKN MSL... WITH A CHANCE OF SHWRS AND TSTMS. SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH... SHOWERS AND THUNDERSTORM ARE EXPECTED TO IMPACT KIPL THIS AFTERNOON...AND KBLH EARLY THIS EVENING ARE CONVECTIVE ACTIVITY BREAKS OUT AS A VERY MOIST AIRMASS BECOMES ENTRENCHED ACROSS THE REGION. THESE STORMS WILL BE CAPABLE OF PRODUCING STRONG GUSTY WINDS AND PERIODS OF HEAVY RAIN AS THEY PASS OVER THE TERMINALS. LIKELY SHOWERS...AND PERHAPS A PERIOD OF STEADY RAIN IS LIKELY LATER TONIGHT AND ON SUNDAY AS THE AIRMASS STABILIZES OUT...BUT STILL REMAINS VERY MOIST...WITH BKN TO OVC MID-LEVEL CIGS WIDESPREAD OVER THE REGION. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... TUESDAY THROUGH SATURDAY... DEEP SOUTHERLY FLOW IS EXPECTED TO BRING IN ABOVE-AVERAGE AMOUNTS OF MOISTURE INTO THE REGION THROUGH THE FORECAST PERIOD...WITH ISOLATED TO SCATTERED THUNDERSTORMS LIKELY EACH AFTERNOON AND EVENING. MINIMUM HUMIDITY VALUES ARE EXPECTED TO FALL INTO THE 25 TO 35 PERCENT RANGE ACROSS THE LOWER DESERTS...AND INTO THE 35 TO 45 PERCENT RANGE ACROSS THE HIGHER ELEVATIONS EACH DAY...WITH VERY GOOD TO EXCELLENT OVERNIGHT RECOVERIES. WINDS ARE EXPECTED TO REMAIN ON THE LIGHT SIDE...EXCEPT NEAR THUNDERSTORMS. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...FLASH FLOOD WATCH FROM LATE TONIGHT THROUGH SUNDAY EVENING AZZ020-021-022-025-026-027. CA...FLASH FLOOD WATCH FROM LATE TONIGHT THROUGH SUNDAY EVENING CAZ030>033. && $$ VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX DISCUSSION...CB PREVIOUS DISCUSSION...AJ/DEWEY AVIATION...VASQUEZ/PERCHA/LEINS FIRE WEATHER...AJ
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
1235 PM MST FRI AUG 23 2013 .SYNOPSIS... INCREASING MOISTURE AND PRECIPITATION CHANCES TODAY THROUGH MONDAY...AS WELL AS A DECREASE IN TEMPERATURES. INCREASED PRECIPITATION CHANCES WILL CONTINUE THROUGH MOST OF NEXT WEEK. && .DISCUSSION... MORNING SATELLITE IMAGERY LOOKS SIMILAR TO YESTERDAY...HOWEVER A BIT LESS CLOUD COVER ACROSS THE STATE. LAST EVENING/S LARGE AREA OF CONVECTION CAN BE SEEN ON RADAR MOVING INTO SOUTHWEST UTAH...AND SOME STREAMS OF LINGERING SHOWERS ACROSS WESTERN MARICOPA COUNTY AT 10 AM MST. 12Z RAOB SOUNDING PWAT VALUES SHOW LITTLE CHANGE FROM YESTERDAY WITH SLIGHT DRYING IN THE MID AND LOW LEVELS ACROSS THE DESERT SOUTHWEST...VALUES 0.7 - 1.4 INCHES ACROSS ARIZONA. WITH THE BOUNDARY LAYER WORKED OVER QUITE WELL IN THE SOUTHWEST CORNER OF ARIZONA LAST EVENING...CONFIDENCE IS HIGHER MOST OF THE CONVECTIVE ACTIVITY WILL REMAIN ACROSS MARICOPA COUNTY AND POINTS EASTWARD. MADE SOME CHANGES TO THE POP GRIDS FOR THE REMAINDER OF TODAY...INCREASING SPACIAL COVERAGE FOR SLIGHT CHANCES TO CHANCES ACROSS THE LOWER DESERTS. TEMPERATURES SHOULD BE SET FOR NOW...ON TRACK TO REACH SEASONAL NORMAL. MORE UPDATES LATER...AS THE PREVIOUS DISCUSSION STILL APPLIES. .PREVIOUS DISCUSSION.../246 AM MST/... EVENING STORM ACTIVITY HAS LARGELY QUIETED DOWN ACROSS THE FORECAST AREA THIS MORNING...WITH MOST OF THE STORMS SHIFTING NORTHWARD OVER NORTHWEST ARIZONA AS OF 09Z. UPPER LEVEL DIFLUENCE IN AN AREA OF 50+KT 250MB WINDS APPEARS TO BE THE DRIVING FORCE FOR THESE STORMS AND WV IMAGERY SUGGESTS THE STORMS SHOULD REMAIN CONFINED TO THE HIGHER TERRAIN NORTH OF THE CWA. LATEST RUN OF THE HRRR MODEL WANTS TO CONTINUE RE-DEVELOPING STORMS AS FAR SOUTH AT YUMA THIS MORNING...BUT THE BOUNDARY LAYER IS NO LONGER SUPPORTIVE OF STORMS SINCE LAST EVENINGS CONVECTION. IN THE VERY SHORT TERM I WILL MAINTAIN A 10-20 POP ACROSS LA PAZ AND FAR NORTHWEST MARICOPA COUNTY IN THE EVENT THESE STORMS BACK-BUILD TO THE SOUTH...OTHERWISE NOT EXPECTING MUCH STORM ACTIVITY FOR THIS MORNING. TOUGH FORECAST FOR THIS AFTERNOON...AS THE TWO MOST RECENT RUNS OF THE SREF PAINT A NEARLY IDENTICAL AREA OF ENHANCED MLCAPES ACROSS WESTERN AND SOUTHERN ARIZONA. MEANWHILE...SLIGHTLY DRIER THAN NORMAL AIR REMAINS IN PLACE FROM CENTRAL NEW MEXICO TO THE MOUNTAINS OF EASTERN ARIZONA. HARD TO ENVISION STORMS FORMING IN THE IDENTICAL AREAS TWO DAYS IN A ROW...ESPECIALLY GIVEN LITTLE RECOVERY TIME FROM THURSDAYS CONVECTIVE OVERTURNING OF THE BOUNDARY LAYER. NONETHELESS...I THINK STORMS ARE POSSIBLE ACROSS PORTIONS OF LA PAZ...YUMA...AND WESTERN MARICOPA COUNTIES. NAMDNG5 AND NMM BASED WRF MODELS ARE THE MOST VIGOROUS WITH THIS AFTERNOONS CONVECTION IN THESE AREAS WHILE ARW BASED MODELS ARE A BIT MORE RESERVED. INHERITED FORECAST DEPICTED 20-30 POPS WEST OF PHOENIX AND THIS STILL LOOKS REASONABLE. TOUGH TO SAY HOW MUCH WILL DEVELOP EAST OF PHOENIX. NOT MUCH IN THE WAY OF FORCING MECHANISMS OR SUBSTANTIAL MOISTURE...BUT THERE IS DECENT POTENTIAL FOR MLCAPES AOA 1000 J/KG. LEFT POPS IN THE 20-30 RANGE IN SOUTHERN GILA CO AS WELL. THE WEEKEND STILL LOOKS TO BE QUITE ACTIVE ACROSS THE REGION...SYNOPTIC SCALE MODEL AGREEMENT CONTINUES FOR AT LEAST THE 3RD OR 4TH DAY IN A ROW. ALL MODELS SUGGEST A SUBSTANTIAL INCREASE IN MOISTURE ON SATURDAY WITH MIXING RATIOS CLIMBING INTO THE 10-12 G/KG RANGE...POSSIBLY TOPPING OUT ABOVE 14 G/KG. PWATS OF 2.0-2.2 INCHES WILL BE COMMON ACROSS SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA THIS WEEKEND WITH SLIGHTLY LOWER VALUES TO THE EAST. THERE ARENT ANY OBVIOUS TROUGHS DEPICTED IN THE FLOW DURING THE DAY ON SATURDAY...BUT MID LEVEL SPEED CONVERGENCE BEGINS TO TAKE SHAPE LATE SATURDAY NIGHT INTO SUNDAY MORNING. I REFINED POPS SLIGHTLY TO SHOW THE HIGHEST VALUES FROM 00Z SUNDAY THROUGH 00Z MONDAY...CERTAINLY A PRETTY LONG BROAD-BRUSHED PERIOD...BUT ONCE STORMS DEVELOP THEY SHOULD HAVE NO PROBLEM MAINTAINING THEMSELVES ACROSS THE ENTIRE REGION. POPS CWA-WIDE HAVE BEEN INCREASED INTO THE 60-80 PERCENT RANGE. WOULD LIKE TO PLACE FURTHER TEMPORAL REFINEMENT INTO THE FORECAST BUT IT WILL BE TOUGH UNTIL STORMS ACTUALLY BEGIN DEVELOPING. UPPER LEVEL SUPPORT WANES SLIGHTLY ON MONDAY AND CONSEQUENTLY I THINK THERE SHOULD BE AN OVERALL DECREASE IN STORM COVERAGE MONDAY/MONDAY NIGHT. THE FORECAST FOR TUESDAY THROUGH NEXT FRIDAY WILL CONSIST OF HIGHER THAN NORMAL POPS AND LOWER THAN NORMAL TEMPS GIVEN SUBSTANTIALLY HIGHER THAN NORMAL MOISTURE VALUES. THE GFS AND EUROPEAN MODELS BOTH ADVERTISE A COUPLE OF EASTERLY WAVES NEXT WEEK...ALTHOUGH EACH MODEL SUGGESTS A DIFFERENT DAY /WEDNESDAY PER GFS...TUESDAY FOR ECMWF/. WITH SUCH HIGH PWATS IN PLACE...TUESDAY AND/OR WEDNESDAY COULD BE VERY ACTIVE IF ONE OF THESE TROUGHS ACTUALLY COME TO PASS AS ADVERTISED. THIS WILL ALSO NEED TO BE LOOKED INTO FURTHER AS THE EVENT GETS CLOSER. && .AVIATION... SOUTH-CENTRAL AND SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA...INCLUDING KPHX...KIWA...KSDL...KIPL...AND KBLH... CONDITIONS REMAIN MOIST AND ISOLATED SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP THIS AFTERNOON ACROSS MUCH OF THE AREA. ACROSS SOUTH-CENTRAL AZ...CONVECTION WILL BE CONCENTRATED ACROSS THE HIGHER TERRAIN MAINLY EAST OF PHOENIX. AT THE PHOENIX TERMINALS...AN OUTFLOW BOUNDARY IS LIKELY TO PRODUCE A WIND SHIFT THIS EVENING...RESULTING IN AN EARLIER ONSET TO THE DRAINAGE FLOW. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... SUNDAY THROUGH THURSDAY... RATHER HUMID CONDITIONS AND WELL BELOW NORMAL TEMPERATURES ARE EXPECTED SUNDAY AS TROPICAL MOISTURE OVERSPREADS ARIZONA AND SOUTHEAST CALIFORNIA. SHOWERS AND THUNDERSTORMS ARE EXPECTED TO AFFECT THE WHOLE FORECAST AREA AT ONE TIME OR ANOTHER SUNDAY INTO MONDAY. HOWEVER...RAINFALL AMOUNTS WILL BE HIGHLY VARIABLE WITH SOME LOCATIONS RECEIVING QUITE A BIT LESS THAN OTHERS. ATMOSPHERIC MOISTURE WILL TREND DOWN MONDAY AND TUESDAY...LEVELING OFF WEDNESDAY AND THURSDAY. STORM CHANCES WILL ALSO TREND DOWNWARD WHILE TEMPERATURES TREND UPWARD. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX DISCUSSION...DEWEY PREVIOUS DISCUSSION...LEINS AVIATION...HIRSCH FIRE WEATHER...AJ
AREA FORECAST DISCUSSION...UPDATED
NWS PHOENIX AZ
1015 AM MST FRI AUG 23 2013 .SYNOPSIS... INCREASING MOISTURE AND PRECIPITATION CHANCES TODAY THROUGH MONDAY...AS WELL AS A DECREASE IN TEMPERATURES. INCREASED PRECIPITATION CHANCES WILL CONTINUE THROUGH MOST OF NEXT WEEK. && .DISCUSSION... MORNING SATELLITE IMAGERY LOOKS SIMILAR TO YESTERDAY...HOWEVER A BIT LESS CLOUD COVER ACROSS THE STATE. LAST EVENING/S LARGE AREA OF CONVECTION CAN BE SEEN ON RADAR MOVING INTO SOUTHWEST UTAH...AND SOME STREAMS OF LINGERING SHOWERS ACROSS WESTERN MARICOPA COUNTY AT 10 AM MST. 12Z RAOB SOUNDING PWAT VALUES SHOW LITTLE CHANGE FROM YESTERDAY WITH SLIGHT DRYING IN THE MID AND LOW LEVELS ACROSS THE DESERT SOUTHWEST...VALUES 0.7 - 1.4 INCHES ACROSS ARIZONA. WITH THE BOUNDARY LAYER WORKED OVER QUITE WELL IN THE SOUTHWEST CORNER OF ARIZONA LAST EVENING...CONFIDENCE IS HIGHER MOST OF THE CONVECTIVE ACTIVITY WILL REMAIN ACROSS MARICOPA COUNTY AND POINTS EASTWARD. MADE SOME CHANGES TO THE POP GRIDS FOR THE REMAINDER OF TODAY...INCREASING SPACIAL COVERAGE FOR SLIGHT CHANCES TO CHANCES ACROSS THE LOWER DESERTS. TEMPERATURES SHOULD BE SET FOR NOW...ON TRACK TO REACH SEASONAL NORMAL. MORE UPDATES LATER...AS THE PREVIOUS DISCUSSION STILL APPLIES. .PREVIOUS DISCUSSION.../246 AM MST/... EVENING STORM ACTIVITY HAS LARGELY QUIETED DOWN ACROSS THE FORECAST AREA THIS MORNING...WITH MOST OF THE STORMS SHIFTING NORTHWARD OVER NORTHWEST ARIZONA AS OF 09Z. UPPER LEVEL DIFLUENCE IN AN AREA OF 50+KT 250MB WINDS APPEARS TO BE THE DRIVING FORCE FOR THESE STORMS AND WV IMAGERY SUGGESTS THE STORMS SHOULD REMAIN CONFINED TO THE HIGHER TERRAIN NORTH OF THE CWA. LATEST RUN OF THE HRRR MODEL WANTS TO CONTINUE RE-DEVELOPING STORMS AS FAR SOUTH AT YUMA THIS MORNING...BUT THE BOUNDARY LAYER IS NO LONGER SUPPORTIVE OF STORMS SINCE LAST EVENINGS CONVECTION. IN THE VERY SHORT TERM I WILL MAINTAIN A 10-20 POP ACROSS LA PAZ AND FAR NORTHWEST MARICOPA COUNTY IN THE EVENT THESE STORMS BACK-BUILD TO THE SOUTH...OTHERWISE NOT EXPECTING MUCH STORM ACTIVITY FOR THIS MORNING. TOUGH FORECAST FOR THIS AFTERNOON...AS THE TWO MOST RECENT RUNS OF THE SREF PAINT A NEARLY IDENTICAL AREA OF ENHANCED MLCAPES ACROSS WESTERN AND SOUTHERN ARIZONA. MEANWHILE...SLIGHTLY DRIER THAN NORMAL AIR REMAINS IN PLACE FROM CENTRAL NEW MEXICO TO THE MOUNTAINS OF EASTERN ARIZONA. HARD TO ENVISION STORMS FORMING IN THE IDENTICAL AREAS TWO DAYS IN A ROW...ESPECIALLY GIVEN LITTLE RECOVERY TIME FROM THURSDAYS CONVECTIVE OVERTURNING OF THE BOUNDARY LAYER. NONETHELESS...I THINK STORMS ARE POSSIBLE ACROSS PORTIONS OF LA PAZ...YUMA...AND WESTERN MARICOPA COUNTIES. NAMDNG5 AND NMM BASED WRF MODELS ARE THE MOST VIGOROUS WITH THIS AFTERNOONS CONVECTION IN THESE AREAS WHILE ARW BASED MODELS ARE A BIT MORE RESERVED. INHERITED FORECAST DEPICTED 20-30 POPS WEST OF PHOENIX AND THIS STILL LOOKS REASONABLE. TOUGH TO SAY HOW MUCH WILL DEVELOP EAST OF PHOENIX. NOT MUCH IN THE WAY OF FORCING MECHANISMS OR SUBSTANTIAL MOISTURE...BUT THERE IS DECENT POTENTIAL FOR MLCAPES AOA 1000 J/KG. LEFT POPS IN THE 20-30 RANGE IN SOUTHERN GILA CO AS WELL. THE WEEKEND STILL LOOKS TO BE QUITE ACTIVE ACROSS THE REGION...SYNOPTIC SCALE MODEL AGREEMENT CONTINUES FOR AT LEAST THE 3RD OR 4TH DAY IN A ROW. ALL MODELS SUGGEST A SUBSTANTIAL INCREASE IN MOISTURE ON SATURDAY WITH MIXING RATIOS CLIMBING INTO THE 10-12 G/KG RANGE...POSSIBLY TOPPING OUT ABOVE 14 G/KG. PWATS OF 2.0-2.2 INCHES WILL BE COMMON ACROSS SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA THIS WEEKEND WITH SLIGHTLY LOWER VALUES TO THE EAST. THERE ARENT ANY OBVIOUS TROUGHS DEPICTED IN THE FLOW DURING THE DAY ON SATURDAY...BUT MID LEVEL SPEED CONVERGENCE BEGINS TO TAKE SHAPE LATE SATURDAY NIGHT INTO SUNDAY MORNING. I REFINED POPS SLIGHTLY TO SHOW THE HIGHEST VALUES FROM 00Z SUNDAY THROUGH 00Z MONDAY...CERTAINLY A PRETTY LONG BROAD-BRUSHED PERIOD...BUT ONCE STORMS DEVELOP THEY SHOULD HAVE NO PROBLEM MAINTAINING THEMSELVES ACROSS THE ENTIRE REGION. POPS CWA-WIDE HAVE BEEN INCREASED INTO THE 60-80 PERCENT RANGE. WOULD LIKE TO PLACE FURTHER TEMPORAL REFINEMENT INTO THE FORECAST BUT IT WILL BE TOUGH UNTIL STORMS ACTUALLY BEGIN DEVELOPING. UPPER LEVEL SUPPORT WANES SLIGHTLY ON MONDAY AND CONSEQUENTLY I THINK THERE SHOULD BE AN OVERALL DECREASE IN STORM COVERAGE MONDAY/MONDAY NIGHT. THE FORECAST FOR TUESDAY THROUGH NEXT FRIDAY WILL CONSIST OF HIGHER THAN NORMAL POPS AND LOWER THAN NORMAL TEMPS GIVEN SUBSTANTIALLY HIGHER THAN NORMAL MOISTURE VALUES. THE GFS AND EUROPEAN MODELS BOTH ADVERTISE A COUPLE OF EASTERLY WAVES NEXT WEEK...ALTHOUGH EACH MODEL SUGGESTS A DIFFERENT DAY /WEDNESDAY PER GFS...TUESDAY FOR ECMWF/. WITH SUCH HIGH PWATS IN PLACE...TUESDAY AND/OR WEDNESDAY COULD BE VERY ACTIVE IF ONE OF THESE TROUGHS ACTUALLY COME TO PASS AS ADVERTISED. THIS WILL ALSO NEED TO BE LOOKED INTO FURTHER AS THE EVENT GETS CLOSER. && .AVIATION... SOUTH-CENTRAL AND SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA...INCLUDING KPHX...KIWA...KSDL...KIPL...AND KBLH... A WEATHER DISTURBANCE OVER WESTERN ARIZONA WILL KEEP CLOUDINESS...AT OR ABOVE 12 KFT MSL...IN PLACE BETWEEN PHOENIX AND FAR SOUTHEAST CALIFORNIA THROUGH THE MORNING BEFORE DECREASING THIS AFTERNOON. SHOWERS WILL BE POSSIBLE IN THAT AREA WITH MORE ACTIVITY OVER NORTHERN ARIZONA AND SOUTHERN NEVADA. ONCE AGAIN...OUTFLOW WINDS FROM DISTANT STORMS WILL BE A DISTINCT POSSIBILITY LATER TODAY/THIS EVENING. THERE WILL BE A SLIGHT CHANCE OF THUNDERSTORMS AT EACH OF THE TAF SITES BUT LESS ACTIVITY IS ANTICIPATED OVER THE LOWER COLORADO RIVER VALLEY AND THE IMPERIAL VALLEY THAN ON THURSDAY. CONFIDENCE IN STORMS OCCURRING OVER ANY GIVEN TAF SITE TOO LOW TO REFLECT IN THE TAFS AT THIS POINT. APART FROM THUNDERSTORMS...WINDS WILL BE LIGHT. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... SUNDAY THROUGH THURSDAY... RATHER HUMID CONDITIONS AND WELL BELOW NORMAL TEMPERATURES ARE EXPECTED SUNDAY AS TROPICAL MOISTURE OVERSPREADS ARIZONA AND SOUTHEAST CALIFORNIA. SHOWERS AND THUNDERSTORMS ARE EXPECTED TO AFFECT THE WHOLE FORECAST AREA AT ONE TIME OR ANOTHER SUNDAY INTO MONDAY. HOWEVER...RAINFALL AMOUNTS WILL BE HIGHLY VARIABLE WITH SOME LOCATIONS RECEIVING QUITE A BIT LESS THAN OTHERS. ATMOSPHERIC MOISTURE WILL TREND DOWN MONDAY AND TUESDAY...LEVELING OFF WEDNESDAY AND THURSDAY. STORM CHANCES WILL ALSO TREND DOWNWARD WHILE TEMPERATURES TREND UPWARD. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX DISCUSSION...DEWEY PREVIOUS DISCUSSION...LEINS AVIATION...AJ FIRE WEATHER...AJ
AREA FORECAST DISCUSSION...UPDATED
NWS PHOENIX AZ
555 AM MST FRI AUG 23 2013 .UPDATE... UPDATED AVIATION AND FIRE WEATHER SECTIONS. && .SYNOPSIS... A GRADUAL INCREASE IN PRECIPITATION CHANCES...AS WELL AS A DECREASE IN TEMPERATURES...IS EXPECTED OVER THE NEXT SEVERAL DAYS AND INTO THIS WEEKEND. INCREASED PRECIPITATION CHANCES WILL CONTINUE THROUGH EARLY NEXT WEEK. && .DISCUSSION... EVENING STORM ACTIVITY HAS LARGELY QUIETED DOWN ACROSS THE FORECAST AREA THIS MORNING...WITH MOST OF THE STORMS SHIFTING NORTHWARD OVER NORTHWEST ARIZONA AS OF 09Z. UPPER LEVEL DIFLUENCE IN AN AREA OF 50+KT 250MB WINDS APPEARS TO BE THE DRIVING FORCE FOR THESE STORMS AND WV IMAGERY SUGGESTS THE STORMS SHOULD REMAIN CONFINED TO THE HIGHER TERRAIN NORTH OF THE CWA. LATEST RUN OF THE HRRR MODEL WANTS TO CONTINUE RE-DEVELOPING STORMS AS FAR SOUTH AT YUMA THIS MORNING...BUT THE BOUNDARY LAYER IS NO LONGER SUPPORTIVE OF STORMS SINCE LAST EVENINGS CONVECTION. IN THE VERY SHORT TERM I WILL MAINTAIN A 10-20 POP ACROSS LA PAZ AND FAR NORTHWEST MARICOPA COUNTY IN THE EVENT THESE STORMS BACK-BUILD TO THE SOUTH...OTHERWISE NOT EXPECTING MUCH STORM ACTIVITY FOR THIS MORNING. TOUGH FORECAST FOR THIS AFTERNOON...AS THE TWO MOST RECENT RUNS OF THE SREF PAINT A NEARLY IDENTICAL AREA OF ENHANCED MLCAPES ACROSS WESTERN AND SOUTHERN ARIZONA. MEANWHILE...SLIGHTLY DRIER THAN NORMAL AIR REMAINS IN PLACE FROM CENTRAL NEW MEXICO TO THE MOUNTAINS OF EASTERN ARIZONA. HARD TO ENVISION STORMS FORMING IN THE IDENTICAL AREAS TWO DAYS IN A ROW...ESPECIALLY GIVEN LITTLE RECOVERY TIME FROM THURSDAYS CONVECTIVE OVERTURNING OF THE BOUNDARY LAYER. NONETHELESS...I THINK STORMS ARE POSSIBLE ACROSS PORTIONS OF LA PAZ...YUMA...AND WESTERN MARICOPA COUNTIES. NAMDNG5 AND NMM BASED WRF MODELS ARE THE MOST VIGOROUS WITH THIS AFTERNOONS CONVECTION IN THESE AREAS WHILE ARW BASED MODELS ARE A BIT MORE RESERVED. INHERITED FORECAST DEPICTED 20-30 POPS WEST OF PHOENIX AND THIS STILL LOOKS REASONABLE. TOUGH TO SAY HOW MUCH WILL DEVELOP EAST OF PHOENIX. NOT MUCH IN THE WAY OF FORCING MECHANISMS OR SUBSTANTIAL MOISTURE...BUT THERE IS DECENT POTENTIAL FOR MLCAPES AOA 1000 J/KG. LEFT POPS IN THE 20-30 RANGE IN SOUTHERN GILA CO AS WELL. THE WEEKEND STILL LOOKS TO BE QUITE ACTIVE ACROSS THE REGION...SYNOPTIC SCALE MODEL AGREEMENT CONTINUES FOR AT LEAST THE 3RD OR 4TH DAY IN A ROW. ALL MODELS SUGGEST A SUBSTANTIAL INCREASE IN MOISTURE ON SATURDAY WITH MIXING RATIOS CLIMBING INTO THE 10-12 G/KG RANGE...POSSIBLY TOPPING OUT ABOVE 14 G/KG. PWATS OF 2.0-2.2 INCHES WILL BE COMMON ACROSS SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA THIS WEEKEND WITH SLIGHTLY LOWER VALUES TO THE EAST. THERE ARENT ANY OBVIOUS TROUGHS DEPICTED IN THE FLOW DURING THE DAY ON SATURDAY...BUT MID LEVEL SPEED CONVERGENCE BEGINS TO TAKE SHAPE LATE SATURDAY NIGHT INTO SUNDAY MORNING. I REFINED POPS SLIGHTLY TO SHOW THE HIGHEST VALUES FROM 00Z SUNDAY THROUGH 00Z MONDAY...CERTAINLY A PRETTY LONG BROAD-BRUSHED PERIOD...BUT ONCE STORMS DEVELOP THEY SHOULD HAVE NO PROBLEM MAINTAINING THEMSELVES ACROSS THE ENTIRE REGION. POPS CWA-WIDE HAVE BEEN INCREASED INTO THE 60-80 PERCENT RANGE. WOULD LIKE TO PLACE FURTHER TEMPORAL REFINEMENT INTO THE FORECAST BUT IT WILL BE TOUGH UNTIL STORMS ACTUALLY BEGIN DEVELOPING. UPPER LEVEL SUPPORT WANES SLIGHTLY ON MONDAY AND CONSEQUENTLY I THINK THERE SHOULD BE AN OVERALL DECREASE IN STORM COVERAGE MONDAY/MONDAY NIGHT. THE FORECAST FOR TUESDAY THROUGH NEXT FRIDAY WILL CONSIST OF HIGHER THAN NORMAL POPS AND LOWER THAN NORMAL TEMPS GIVEN SUBSTANTIALLY HIGHER THAN NORMAL MOISTURE VALUES. THE GFS AND EUROPEAN MODELS BOTH ADVERTISE A COUPLE OF EASTERLY WAVES NEXT WEEK...ALTHOUGH EACH MODEL SUGGESTS A DIFFERENT DAY /WEDNESDAY PER GFS...TUESDAY FOR ECMWF/. WITH SUCH HIGH PWATS IN PLACE...TUESDAY AND/OR WEDNESDAY COULD BE VERY ACTIVE IF ONE OF THESE TROUGHS ACTUALLY COME TO PASS AS ADVERTISED. THIS WILL ALSO NEED TO BE LOOKED INTO FURTHER AS THE EVENT GETS CLOSER. && .AVIATION... SOUTH-CENTRAL AND SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA...INCLUDING KPHX...KIWA...KSDL...KIPL...AND KBLH... A WEATHER DISTURBANCE OVER WESTERN ARIZONA WILL KEEP CLOUDINESS...AT OR ABOVE 12 KFT MSL...IN PLACE BETWEEN PHOENIX AND FAR SOUTHEAST CALIFORNIA THROUGH THE MORNING BEFORE DECREASING THIS AFTERNOON. SHOWERS WILL BE POSSIBLE IN THAT AREA WITH MORE ACTIVITY OVER NORTHERN ARIZONA AND SOUTHERN NEVADA. ONCE AGAIN...OUTFLOW WINDS FROM DISTANT STORMS WILL BE A DISTINCT POSSIBILITY LATER TODAY/THIS EVENING. THERE WILL BE A SLIGHT CHANCE OF THUNDERSTORMS AT EACH OF THE TAF SITES BUT LESS ACTIVITY IS ANTICIPATED OVER THE LOWER COLORADO RIVER VALLEY AND THE IMPERIAL VALLEY THAN ON THURSDAY. CONFIDENCE IN STORMS OCCURRING OVER ANY GIVEN TAF SITE TOO LOW TO REFLECT IN THE TAFS AT THIS POINT. APART FROM THUNDERSTORMS...WINDS WILL BE LIGHT. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... SUNDAY THROUGH THURSDAY... RATHER HUMID CONDITIONS AND WELL BELOW NORMAL TEMPERATURES ARE EXPECTED SUNDAY AS TROPICAL MOISTURE OVERSPREADS ARIZONA AND SOUTHEAST CALIFORNIA. SHOWERS AND THUNDERSTORMS ARE EXPECTED TO AFFECT THE WHOLE FORECAST AREA AT ONE TIME OR ANOTHER SUNDAY INTO MONDAY. HOWEVER...RAINFALL AMOUNTS WILL BE HIGHLY VARIABLE WITH SOME LOCATIONS RECEIVING QUITE A BIT LESS THAN OTHERS. ATMOSPHERIC MOISTURE WILL TREND DOWN MONDAY AND TUESDAY...LEVELING OFF WEDNESDAY AND THURSDAY. STORM CHANCES WILL ALSO TREND DOWNWARD WHILE TEMPERATURES TREND UPWARD. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX DISCUSSION...LEINS AVIATION...AJ FIRE WEATHER...AJ
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
246 AM MST FRI AUG 23 2013 .SYNOPSIS... A GRADUAL INCREASE IN PRECIPITATION CHANCES...AS WELL AS A DECREASE IN TEMPERATURES...IS EXPECTED OVER THE NEXT SEVERAL DAYS AND INTO THIS WEEKEND. INCREASED PRECIPITATION CHANCES WILL CONTINUE THROUGH EARLY NEXT WEEK. && .DISCUSSION... EVENING STORM ACTIVITY HAS LARGELY QUIETED DOWN ACROSS THE FORECAST AREA THIS MORNING...WITH MOST OF THE STORMS SHIFTING NORTHWARD OVER NORTHWEST ARIZONA AS OF 09Z. UPPER LEVEL DIFLUENCE IN AN AREA OF 50+KT 250MB WINDS APPEARS TO BE THE DRIVING FORCE FOR THESE STORMS AND WV IMAGERY SUGGESTS THE STORMS SHOULD REMAIN CONFINED TO THE HIGHER TERRAIN NORTH OF THE CWA. LATEST RUN OF THE HRRR MODEL WANTS TO CONTINUE RE-DEVELOPING STORMS AS FAR SOUTH AT YUMA THIS MORNING...BUT THE BOUNDARY LAYER IS NO LONGER SUPPORTIVE OF STORMS SINCE LAST EVENINGS CONVECTION. IN THE VERY SHORT TERM I WILL MAINTAIN A 10-20 POP ACROSS LA PAZ AND FAR NORTHWEST MARICOPA COUNTY IN THE EVENT THESE STORMS BACK-BUILD TO THE SOUTH...OTHERWISE NOT EXPECTING MUCH STORM ACTIVITY FOR THIS MORNING. TOUGH FORECAST FOR THIS AFTERNOON...AS THE TWO MOST RECENT RUNS OF THE SREF PAINT A NEARLY IDENTICAL AREA OF ENHANCED MLCAPES ACROSS WESTERN AND SOUTHERN ARIZONA. MEANWHILE...SLIGHTLY DRIER THAN NORMAL AIR REMAINS IN PLACE FROM CENTRAL NEW MEXICO TO THE MOUNTAINS OF EASTERN ARIZONA. HARD TO ENVISION STORMS FORMING IN THE IDENTICAL AREAS TWO DAYS IN A ROW...ESPECIALLY GIVEN LITTLE RECOVERY TIME FROM THURSDAYS CONVECTIVE OVERTURNING OF THE BOUNDARY LAYER. NONETHELESS...I THINK STORMS ARE POSSIBLE ACROSS PORTIONS OF LA PAZ...YUMA...AND WESTERN MARICOPA COUNTIES. NAMDNG5 AND NMM BASED WRF MODELS ARE THE MOST VIGOROUS WITH THIS AFTERNOONS CONVECTION IN THESE AREAS WHILE ARW BASED MODELS ARE A BIT MORE RESERVED. INHERITED FORECAST DEPICTED 20-30 POPS WEST OF PHOENIX AND THIS STILL LOOKS REASONABLE. TOUGH TO SAY HOW MUCH WILL DEVELOP EAST OF PHOENIX. NOT MUCH IN THE WAY OF FORCING MECHANISMS OR SUBSTANTIAL MOISTURE...BUT THERE IS DECENT POTENTIAL FOR MLCAPES AOA 1000 J/KG. LEFT POPS IN THE 20-30 RANGE IN SOUTHERN GILA CO AS WELL. THE WEEKEND STILL LOOKS TO BE QUITE ACTIVE ACROSS THE REGION...SYNOPTIC SCALE MODEL AGREEMENT CONTINUES FOR AT LEAST THE 3RD OR 4TH DAY IN A ROW. ALL MODELS SUGGEST A SUBSTANTIAL INCREASE IN MOISTURE ON SATURDAY WITH MIXING RATIOS CLIMBING INTO THE 10-12 G/KG RANGE...POSSIBLY TOPPING OUT ABOVE 14 G/KG. PWATS OF 2.0-2.2 INCHES WILL BE COMMON ACROSS SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA THIS WEEKEND WITH SLIGHTLY LOWER VALUES TO THE EAST. THERE ARENT ANY OBVIOUS TROUGHS DEPICTED IN THE FLOW DURING THE DAY ON SATURDAY...BUT MID LEVEL SPEED CONVERGENCE BEGINS TO TAKE SHAPE LATE SATURDAY NIGHT INTO SUNDAY MORNING. I REFINED POPS SLIGHTLY TO SHOW THE HIGHEST VALUES FROM 00Z SUNDAY THROUGH 00Z MONDAY...CERTAINLY A PRETTY LONG BROAD-BRUSHED PERIOD...BUT ONCE STORMS DEVELOP THEY SHOULD HAVE NO PROBLEM MAINTAINING THEMSELVES ACROSS THE ENTIRE REGION. POPS CWA-WIDE HAVE BEEN INCREASED INTO THE 60-80 PERCENT RANGE. WOULD LIKE TO PLACE FURTHER TEMPORAL REFINEMENT INTO THE FORECAST BUT IT WILL BE TOUGH UNTIL STORMS ACTUALLY BEGIN DEVELOPING. UPPER LEVEL SUPPORT WANES SLIGHTLY ON MONDAY AND CONSEQUENTLY I THINK THERE SHOULD BE AN OVERALL DECREASE IN STORM COVERAGE MONDAY/MONDAY NIGHT. THE FORECAST FOR TUESDAY THROUGH NEXT FRIDAY WILL CONSIST OF HIGHER THAN NORMAL POPS AND LOWER THAN NORMAL TEMPS GIVEN SUBSTANTIALLY HIGHER THAN NORMAL MOISTURE VALUES. THE GFS AND EUROPEAN MODELS BOTH ADVERTISE A COUPLE OF EASTERLY WAVES NEXT WEEK...ALTHOUGH EACH MODEL SUGGESTS A DIFFERENT DAY /WEDNESDAY PER GFS...TUESDAY FOR ECMWF/. WITH SUCH HIGH PWATS IN PLACE...TUESDAY AND/OR WEDNESDAY COULD BE VERY ACTIVE IF ONE OF THESE TROUGHS ACTUALLY COME TO PASS AS ADVERTISED. THIS WILL ALSO NEED TO BE LOOKED INTO FURTHER AS THE EVENT GETS CLOSER. && .AVIATION... SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA AND KSDL... THICKER MID/HIGH CLOUDS WILL PREVAIL THROUGH FRIDAY MORNING...WITH PRIMARY AVIATION IMPACT BEING POTENTIAL WIND SHIFTS AND THE OUTSIDE CHANCE OF SHRA/TSRA REACHING TERMINALS THROUGH FRIDAY MORNING. OUTFLOW BOUNDARIES HAVE LARGELY DISSIPATED THIS EVENING...THOUGH AN EVENTUAL EASTERLY DRAINAGE WIND SHOULD DEVELOP BY THE OVERNIGHT HOURS. RENEWED SHRA/TSRA MAY BE POSSIBLE FRIDAY AFTERNOON THOUGH CONFIDENCE IS TOO LOW TO INCLUDE ANY MENTION AT THIS TIME. SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH... OUTFLOW AND VCTS MAY CONTINUE TO AFFECT APPROACHES INTO KBLH BEFORE MIDNIGHT...WITH ONLY SHIFTING WINDS AND RESIDUAL DUST AFFECTING KIPL. A MORE GENERAL CALM IN WEATHER CONDITIONS SHOULD BE EXPECTED THROUGH FRIDAY MORNING...THOUGH SFC WINDS MAY CONTINUE TO REMAIN RATHER VARIABLE THROUGH THE PERIOD. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... SATURDAY THROUGH WEDNESDAY... MODELS CONTINUE TO DEPICT MOISTURE FROM TROPICAL ORIGINS MAKING ITS WAY INTO THE DESERT SOUTHWEST THIS WEEKEND. THUS HUMIDITIES WILL INCREASE SUBSTANTIALLY ALONG WITH PRECIPITATION CHANCES. TEMPERATURES WILL DECREASE...TO WELL BELOW NORMAL BY SUNDAY...BEFORE INCREASING TO NEAR NORMAL BY TUESDAY AND WEDNESDAY. STRONGER SOUTHERLY WINDS ARE ALSO EXPECTED ON SATURDAY...MAINLY OVER SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA...WITH LESS BREEZINESS THEREAFTER EXCEPT FOR THUNDERSTORM DRIVEN WINDS. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX DISCUSSION...LEINS AVIATION...MO FIRE WEATHER...AJ
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1013 AM MDT FRI AUG 23 2013 .UPDATE...WITH LINGERING CLOUD COVER...HAVE ADJUSTED MAX TEMPERATURES DOWN A COUPLE DEGREES...MAINLY OVER THE DENVER METRO AREA AND FOOTHILLS. WATER VAPOR SATELLITE STILL SHOWING PLENTY OF MOISTURE ROTATING AROUND THE STATE...HOWEVER PRECIPITABLE WATER VALUES OVER NORTHEAST CO ARE DOWN 0.3 INCHES FROM YESTERDAY AT THE SAME TIME. MODELS STILL ADVERTISING DRIER AIR MOVING NORTH FROM NEW MEXICO...HOWEVER BELIEVE LAST NIGHTS/THIS MORNINGS MCS OVER THE STATE MAY HAVE DELAYED IT A BIT. STILL EXPECTING DRIER AIR TO BEGIN TO MOVE UP FROM THE SOUTH LATER TODAY WHICH WILL LIMIT STORM ACTIVITY OVER THE PLAINS...MAINLY SOUTH OF I76. ENOUGH INSTABILITY OVER THE MOUNTAINS AND OVER CHEYENNE RIDGE WILL ALLOW SCATTERED STORMS TO ONCE AGAIN FORM TODAY. && .AVIATION...LIGHT WINDS NEAR THE AIRPORT SHOULD BEGIN TRANSITIONING TO BE OUT OF THE NORTHEAST AS SOUTHERLY WINDS OVER THE EASTERN PLAINS CYCLONE INTO THE AREA. THERE WILL BE A CHANCE FOR THUNDERSTORMS THIS AFTERNOON...MAINLY FROM 21-01Z. HEAVY RAIN AND WIND GUSTS TO 40 KNOTS WILL BE POSSIBLE WITH THE STRONGER STORMS. HIGH-RES MODELS POINTING TO THE HIGHER TERRAIN OF PARK AND JEFFERSON COUNTIES WITH SLIGHTLY MORE COVERAGE EARLIER ON THEN BRING IT NORTHEAST TOWARD THE METRO AREAS. THIS WOULD LIKELY TURN WINDS BACK FROM THE SOUTH. DRIER AIR WILL MOVE INTO THE AREA TONIGHT AND BRING CLEARING SKIES. && .PREV DISCUSSION... /ISSUED 338 AM MDT FRI AUG 23 2013/ SHORT TERM...SOUTHWEST FLOW ALOFT WILL PREVAIL AS THE UPPER LEVEL HIGH SHIFTS EASTWARD TODAY. A LOW PRESSURE SYSTEM WILL FORM OVER SOUTHERN ALBERTA DURING THE DAY AND A LOW PRESSURE TROUGH WILL EXTEND SOUTHWARD ALONG THE LEE SIDE OF THE ROCKIES AND INTO COLORADO. THIS WILL PRODUCE SOUTHERLY WINDS OVER EASTERN COLORADO. DRIER OVER NEW MEXICO WILL BE PULLED NORTHWARD THROUGH THE DAY. THE LATEST RAP SHOWS THE AIRMASS WILL STAY MOIST TODAY WITH PRECIPITABLE WATER VALUES OF AN INCH TO 1.25 AND CAPES OF 1000 TO 1500 J/KG. THIS WOULD SUPPORT ANOTHER ROUND OF STRONG THUNDERSTORMS. THE NAM AND GFS HAS PRECIPITABLE WATER VALUES OF 0.75 TO ONE INCH WITH CAPES LESS THAN 700 J/KG. WHAT ACTUALLY HAPPENS WILL PROBABLY BE SOMEWHERE IN BETWEEN THESE SOLUTIONS. WILL HAVE THE HIGHEST POPS OVER THE MOUNTAINS AND ACROSS THE NORTHERN ZONES. ALL THE MODELS HAVE SOME DRYING OVER THE SOUTHEAST ZONES AND IT SPREADS NORTH DURING THE EVENING...THUS WILL HAVE THE LOWEST POPS HERE. EXPECT THE CONVECTION TO END DURING THE EVENING HOURS AS DRIER AIR MOVES INTO THE AREA. TEMPERATURES WILL BE A FEW DEGREES WARMER TODAY. CLEARING SKIES THIS MORNING AND EARLY AFTERNOON SHOULD ALLOW ENOUGH SUN TO PUSH HIGHS IN THE UPPER 80S AND PERHAPS LOWER 90S. AS DRIER MOVES INTO THE AREA TONIGHT...TEMPERATURES WILL FALL INTO THE 50S. LONG TERM...MODELS SHOW THE UPPER RIDGE CENTERED OVER CENTRAL KANSAS SATURDAY MORNING. IT MOVES INTO EASTERN KANSAS BY SUNDAY NIGHT. THE FLOW ALOFT STAYS SOUTHWESTERLY OVER THE FORECAST AREA ALL FOUR PERIODS. THE QG VERTICAL VELOCITY FIELD KEEP BENIGN SYNOPTIC SCALE ENERGY OVER THE CWA THROUGH THE PERIOD. THE BOUNDARY LAYER FLOW IS PROGGED TO BE PRETTY MUCH NORMAL DIURNAL PATTERNS THROUGH SUNDAY NIGHT. FOR MOISTURE...MODELS SHOW A FAIR AMOUNTS LATE DAY SATURDAY AND LATE DAY SUNDAY...BUT IT IS IN THE MID AND UPPER LEVELS. THE BOUNDARY LAYER DEW POINT VALUES ARE PROGGED IN THE 40S TO LOWER 50S F FOR THE PLAINS LATE DAY SATURDAY...AND A TAD HIGHER LATE DAY SUNDAY. PRECIPITABLE WATER VALUES ARE IN THE 0.65 TO 1.10 INCH RANGE OVER THE PLAINS SATURDAY THROUGH SUNDAY NIGHT. THE HIGHEST VALUES ARE OUT EAST. THE CAPE IS PRETTY LOW FOR LATE DAY SATURDAY...WITH THE HIGHEST VALUES OVER THE FOOTHILLS. THEY GET UP 750 J/KG AT BEST THERE...WITH VALUES OVER THE PLAINS FROM 100-500 J/KG. THERE IS EVEN LESS CAPE LATE DAY SUNDAY FOR ALL AREAS. MEASURABLE RAINFALL IS PRETTY SPARSE ON THE QPF FIELDS. THERE IS SOME LATE DAY SATURDAY OVER THE WESTERN HALF OF THE CWA...THEN A TAD BIT LESS LATE DAY SUNDAY. FOR POPS...20-30%S IN THE MOUNTAINS SHOULD DO FOR THE LATE DAYS AND 0-10%S OVER THE PLAINS. FOR TEMPERATURES...SATURDAY`S HIGHS ARE 1-2 C WARMER THAN TODAY`S EXPECTED HIGHS. SUNDAY`S ARE CLOSE TO SATURDAY`S. FOR THE LATER DAYS...MONDAY THROUGH THURSDAY...MODELS KEEP THE UPPER RIDGE CENTERED OVER KANSAS ALL FOUR DAYS. THE SOUTHWESTERLY FLOW ALOFT STAYS AROUND FOR THE CWA AS WELL...BUT MOISTURE IS SPARSE. TEMPERATURES LOOK TO STAY A BIT ABOVE SEASONAL NORMALS. AVIATION...SLIGHT CHANCE FOR PATCHY FOG AND LOW CLOUDS THIS MORNING...NOT ENOUGH OF A CHANCE TO MENTION IN THE TAFS. THERE WILL BE A CHANCE FOR THUNDERSTORMS THIS AFTERNOON...MAINLY FROM 20-01Z. HEAVY RAIN AND WIND GUSTS TO 40 KNOTS WILL BE POSSIBLE WITH THE STRONGER STORMS. DRIER AIR WILL MOVE INTO THE AREA TONIGHT AND BRING CLEARING SKIES. SOUTHERLY WINDS ARE EXPECTED FOR MOST OF THE DAY. HYDROLOGY...ANOTHER ROUND OF THUNDERSTORMS WILL FORM OVER THE HIGHER TERRAIN AND SPREAD EASTWARD. HEAVY RAIN WILL AGAIN BE POSSIBLE WITH THE STORMS WITH 1 INCH IN 15 TO 20 MINUTES OCCURRING. FLASHING FLOODING COULD OCCUR IF A STRONG STORM FORMS OVER THE BURN AREAS. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...MEIER LONG TERM....RJK UPDATE/AVIATION...KRIEDERMAN
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
338 AM MDT FRI AUG 23 2013 .SHORT TERM...SOUTHWEST FLOW ALOFT WILL PREVAIL AS THE UPPER LEVEL HIGH SHIFTS EASTWARD TODAY. A LOW PRESSURE SYSTEM WILL FORM OVER SOUTHERN ALBERTA DURING THE DAY AND A LOW PRESSURE TROUGH WILL EXTEND SOUTHWARD ALONG THE LEE SIDE OF THE ROCKIES AND INTO COLORADO. THIS WILL PRODUCE SOUTHERLY WINDS OVER EASTERN COLORADO. DRIER OVER NEW MEXICO WILL BE PULLED NORTHWARD THROUGH THE DAY. THE LATEST RAP SHOWS THE AIRMASS WILL STAY MOIST TODAY WITH PRECIPITABLE WATER VALUES OF AN INCH TO 1.25 AND CAPES OF 1000 TO 1500 J/KG. THIS WOULD SUPPORT ANOTHER ROUND OF STRONG THUNDERSTORMS. THE NAM AND GFS HAS PRECIPITABLE WATER VALUES OF 0.75 TO ONE INCH WITH CAPES LESS THAN 700 J/KG. WHAT ACTUALLY HAPPENS WILL PROBABLY BE SOMEWHERE IN BETWEEN THESE SOLUTIONS. WILL HAVE THE HIGHEST POPS OVER THE MOUNTAINS AND ACROSS THE NORTHERN ZONES. ALL THE MODELS HAVE SOME DRYING OVER THE SOUTHEAST ZONES AND IT SPREADS NORTH DURING THE EVENING...THUS WILL HAVE THE LOWEST POPS HERE. EXPECT THE CONVECTION TO END DURING THE EVENING HOURS AS DRIER AIR MOVES INTO THE AREA. TEMPERATURES WILL BE A FEW DEGREES WARMER TODAY. CLEARING SKIES THIS MORNING AND EARLY AFTERNOON SHOULD ALLOW ENOUGH SUN TO PUSH HIGHS IN THE UPPER 80S AND PERHAPS LOWER 90S. AS DRIER MOVES INTO THE AREA TONIGHT...TEMPERATURES WILL FALL INTO THE 50S. .LONG TERM...MODELS SHOW THE UPPER RIDGE CENTERED OVER CENTRAL KANSAS SATURDAY MORNING. IT MOVES INTO EASTERN KANSAS BY SUNDAY NIGHT. THE FLOW ALOFT STAYS SOUTHWESTERLY OVER THE FORECAST AREA ALL FOUR PERIODS. THE QG VERTICAL VELOCITY FIELD KEEP BENIGN SYNOPTIC SCALE ENERGY OVER THE CWA THROUGH THE PERIOD. THE BOUNDARY LAYER FLOW IS PROGGED TO BE PRETTY MUCH NORMAL DIURNAL PATTERNS THROUGH SUNDAY NIGHT. FOR MOISTURE...MODELS SHOW A FAIR AMOUNTS LATE DAY SATURDAY AND LATE DAY SUNDAY...BUT IT IS IN THE MID AND UPPER LEVELS. THE BOUNDARY LAYER DEW POINT VALUES ARE PROGGED IN THE 40S TO LOWER 50S F FOR THE PLAINS LATE DAY SATURDAY...AND A TAD HIGHER LATE DAY SUNDAY. PRECIPITABLE WATER VALUES ARE IN THE 0.65 TO 1.10 INCH RANGE OVER THE PLAINS SATURDAY THROUGH SUNDAY NIGHT. THE HIGHEST VALUES ARE OUT EAST. THE CAPE IS PRETTY LOW FOR LATE DAY SATURDAY...WITH THE HIGHEST VALUES OVER THE FOOTHILLS. THEY GET UP 750 J/KG AT BEST THERE...WITH VALUES OVER THE PLAINS FROM 100-500 J/KG. THERE IS EVEN LESS CAPE LATE DAY SUNDAY FOR ALL AREAS. MEASURABLE RAINFALL IS PRETTY SPARSE ON THE QPF FIELDS. THERE IS SOME LATE DAY SATURDAY OVER THE WESTERN HALF OF THE CWA...THEN A TAD BIT LESS LATE DAY SUNDAY. FOR POPS...20-30%S IN THE MOUNTAINS SHOULD DO FOR THE LATE DAYS AND 0-10%S OVER THE PLAINS. FOR TEMPERATURES...SATURDAY`S HIGHS ARE 1-2 C WARMER THAN TODAY`S EXPECTED HIGHS. SUNDAY`S ARE CLOSE TO SATURDAY`S. FOR THE LATER DAYS...MONDAY THROUGH THURSDAY...MODELS KEEP THE UPPER RIDGE CENTERED OVER KANSAS ALL FOUR DAYS. THE SOUTHWESTERLY FLOW ALOFT STAYS AROUND FOR THE CWA AS WELL...BUT MOISTURE IS SPARSE. TEMPERATURES LOOK TO STAY A BIT ABOVE SEASONAL NORMALS. && .AVIATION...SLIGHT CHANCE FOR PATCHY FOG AND LOW CLOUDS THIS MORNING...NOT ENOUGH OF A CHANCE TO MENTION IN THE TAFS. THERE WILL BE A CHANCE FOR THUNDERSTORMS THIS AFTERNOON...MAINLY FROM 20-01Z. HEAVY RAIN AND WIND GUSTS TO 40 KNOTS WILL BE POSSIBLE WITH THE STRONGER STORMS. DRIER AIR WILL MOVE INTO THE AREA TONIGHT AND BRING CLEARING SKIES. SOUTHERLY WINDS ARE EXPECTED FOR MOST OF THE DAY. && .HYDROLOGY...ANOTHER ROUND OF THUNDERSTORMS WILL FORM OVER THE HIGHER TERRAIN AND SPREAD EASTWARD. HEAVY RAIN WILL AGAIN BE POSSIBLE WITH THE STORMS WITH 1 INCH IN 15 TO 20 MINUTES OCCURRING. FLASHING FLOODING COULD OCCUR IF A STRONG STORM FORMS OVER THE BURN AREAS. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...MEIER LONG TERM....RJK AVIATION...MEIER
AREA FORECAST DISCUSSION
NWS ALBANY NY
421 PM EDT FRI AUG 23 2013 .SYNOPSIS... HIGH PRESSURE WILL BUILD EASTWARD FROM THE GREAT LAKES REGION INTO THE NORTHEAST THROUGH SATURDAY...WITH A NORTHERLY FLOW BRINGING COOLER TEMPERATURES AND COMFORTABLE HUMIDITY LEVELS. THE SURFACE ANTICYCLONE WILL DRIFT EAST OF NEW JERSEY ON SUNDAY WITH CONTINUED FAIR WEATHER BUT WITH A SOUTHWEST FLOW AND SLIGHTLY WARMER TEMPERATURES. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... AS OF 415 PM EDT...PARTLY TO MOSTLY SUNNY SKIES PREVAIL ACROSS THE REGION...WITH MOST OF THE CLOUDS CONFINED TO HIGHER TERRAIN WEST AND EAST OF THE HUDSON RIVER VALLEY. THESE CLOUDS SHOULD GRADUALLY DISSIPATE AROUND...OR JUST AFTER SUNSET...LEAVING MOSTLY CLEAR TO CLEAR SKIES FOR THE OVERNIGHT HOURS. THE LATEST RUC13 SUGGESTS A SECONDARY SURGE OF LOW LEVEL...DRY AIR ADVECTING SOUTHWARD EARLY TONIGHT. THIS MAY ACT TO KEEP THE BOUNDARY LAYER SOMEWHAT MIXED...PARTICULARLY IN THE HUDSON VALLEY REGION...WITH A N/NE WIND PERSISTING WELL INTO THE OVERNIGHT HOURS...WHICH MAY PRECLUDE FOG FORMATION AND ALSO VERY COOL TEMPS FROM OCCURRING. THEREFORE...HAVE KEPT OUT MENTION OF PATCHY FOG...AND HAVE INDICATED MIN TEMPS IN THE MID 40S TO LOWER 50S IN MOST AREAS...WITH SOME LOWER 40S POSSIBLE ACROSS PORTIONS OF THE WESTERN ADIRONDACKS. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY NIGHT/... SAT-SUN...HIGH PRESSURE SHOULD PROVIDE GENERALLY CLEAR/SUNNY SKIES FOR SAT...WITH JUST OCCASIONAL PASSING HIGH CLOUDS POSSIBLE LATE SAT NT INTO SUNDAY. MIXING DEPTHS MAY BE SOMEWHAT SHALLOW FOR SAT...COMPARED TO RECENT DAYS...GENERALLY UP TO BETWEEN 900 AND 875 MB. THIS SHOULD ALLOW FOR MAX TEMPS TO REACH 75-80 IN MOST VALLEY AREAS...AND UPPER 60S TO LOWER/MID 70S ACROSS HIGHER ELEVATIONS. FOR SAT NT/SUN AM...MIN TEMPS COULD BE A BIT COOLER THAN TONIGHT...ESP SHOULD ANY HIGH CLOUDS HOLD OFF OR REMAIN VERY THIN. HOWEVER...WITH LESS MIXING AND WIND COMPARED TO TONIGHT...THE POTENTIAL FOR AT LEAST PATCHY GROUND FOG WILL BE GREATER...WHICH COULD KEEP AREAS IMMEDIATELY ADJACENT TO BODIES OF WATER A BIT WARMER. HAVE GENERALLY SIDED A BIT CLOSER TO THE COOLER MAV MOS IN MOST AREAS...WITH MIN TEMPS FALLING INTO THE MID 40S TO LOWER 50S IN MOST VALLEY AREAS...AND MAINLY LOWER/MID 40S ACROSS HIGHER ELEVATIONS ACROSS WESTERN NEW ENGLAND...AND THE EASTERN CATSKILLS/WESTERN ADIRONDACKS. ACROSS SOME SHELTERED PORTIONS OF THE SOUTHERN ADIRONDACKS...AND EASTERN CATSKILLS...SOME UPPER 30S COULD EVEN OCCUR BY DAYBREAK SUNDAY. AFTER THE CHILLY START...EXPECT SLIGHTLY DEEPER MIXING WITH A DEVELOPING SOUTHWEST LOW LEVEL FLOW TO ALLOW FOR WARMER MAX TEMPS ON SUNDAY...WITH UPPER 70S TO LOWER 80S IN MOST VALLEYS...AND 70-75 FOR HIGHER ELEVATIONS. SUN NT-MON NT...FORECAST UNCERTAINTY INCREASES DURING THIS PERIOD AS LOW/MID LEVEL WARM ADVECTION STRENGTHENS LATE SUN NT INTO MONDAY...IN RESPONSE TO A POTENTIAL MID LEVEL DISTURBANCE APPROACHING FROM THE GREAT LAKES REGION. THIS PATTERN SHOULD ALLOW FOR INCREASING CLOUDS LATE SUN NT...WITH THE POSSIBILITY OF SHOWERS FOR MON-MON NT. SOME THUNDERSTORMS COULD OCCUR AS WELL...ESP LATE MON INTO MON NT AS ELEVATED INSTABILITY DEVELOPS. EXPECT OVERNIGHT MIN TEMPS TO BE WARMER...WITH MAINLY LOWER/MID 60S FOR VALLEY AREAS...AND 55-60 ACROSS HIGHER ELEVATIONS. MON MAX TEMPS SHOULD REACH THE MID 70S TO LOWER 80S...ALTHOUGH SHOULD WIDESPREAD SHOWERS OR A PERIOD OF STEADIER RAIN OCCUR...EVEN COOLER MAX TEMPS COULD OCCUR. && .LONG TERM /TUESDAY THROUGH FRIDAY/... A CONTINUOUS PATTERN OF DISTURBANCES THAT ARE POTENTIAL RIDGE ROLLERS SHOULD FLOW FROM NORTHWEST TO SOUTHEAST ON THE NORTHEAST SIDE OF A BROAD UPPER LEVEL HIGH PRESSURE...CENTERED OVER THE CENTRAL PLAINS...WHICH WILL AFFECT OUR WEATHER FOR THE EXTENDED PERIOD. CURRENT THINKING IS THAT THE 12Z MODELS ARE A BIT DISORGANIZED DUE TO THE EXTENT OF THE RIDGE ITSELF THAT WILL DICTATE THE SYNOPTIC TRACK OF THESE LOW PRESSURE IMPULSES AS THEY MOVE ON THE OUTSKIRTS OF THE HIGH PRESSURE SYSTEM. CHANCE POPS WILL BE THROUGHOUT THE EXTENDED PERIOD TO INCORPORATE THE DIFFERENT PROBABILITY BLENDS IN THE FORECAST. OUR BEST CHANCE FOR SHOWERS AND THUNDERSTORMS ASSOCIATED WITH AN UPPER LEVEL POSITIVE TILTED TROUGH WITH A POSSIBLE DEVELOPING SURFACE LOW PRESSURE NEAR THE US/CANADA BORDER WILL BE ON WEDNESDAY NIGHT INTO THURSDAY MORNING. THE GENERAL CONSENSUS AS OF NOW SHOWS CLEARING IN THE AREA LATE THURSDAY MORNING AS THE RIDGE FROM THE CENTRAL PLAINS SHIFTS EAST AND HAS MORE OF AN INFLUENCE ON OUR WEATHER PATTERN...GIVING TRANQUIL CONDITIONS FOR THE DAY ON FRIDAY. A WARM UP TO ABOVE AVERAGE TEMPERATURES GOING FROM FRIDAY INTO NEXT WEEKEND IS POSSIBLE AS THE RIDGE CONTINUES TO MOVE EAST NORTHEAST INTO OUR REGION. HIGH TEMPERATURES THROUGHOUT THE EXTENDED PERIOD WILL RANGE FROM THE MID AND UPPER 70S IN THE HIGH TERRAIN TO LOWER 80S IN VALLEY LOCATIONS. LOW TEMPERATURES WILL RANGE FROM THE UPPER 50S TO MID 60S FOR THE ENTIRE REGION. && .AVIATION /20Z FRIDAY THROUGH WEDNESDAY/... THE MAJORITY OF THE UPCOMING TAF PERIOD WILL BE VFR. SOME MORNING FOG IS POSSIBLE AT KGFL...WHERE IT COULD BE LOCALLY DENSE RESULTING IN LIFR CONDITIONS...AND AT KPSF WHERE MVFR IS MORE LIKELY. A LIGHT NORTHERLY FLOW AND DRY AIR ADVECTION WILL RESULT IN MODERATE MIXING OVERNIGHT SO FOG IS NOT EXPECTED AT KALB AND KPOU. NORTHWEST TO NORTH WINDS AROUND 10 KNOTS TODAY WILL DIMINISH THIS EVENING BECOMING CALM OVERNIGHT. LIGHT NORTHERLY WINDS ARE AGAIN EXPECTED ON SATURDAY. OUTLOOK... SATURDAY NIGHT: NO OPERATIONAL IMPACT. PATCHY FG. SUNDAY: NO OPERATIONAL IMPACT. NO SIG WX. SUNDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA. MONDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA. MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA. TUESDAY: MODERATE OPERATIONAL IMPACT. SCATTERED SHRA...TSRA. TUESDAY NIGHT: LOW OPERATIONAL IMPACT. ISOLATED SHRA...TSRA. WEDNESDAY: MODERATE OPERATIONAL IMPACT. SCATTERED SHRA...TSRA. && .FIRE WEATHER... NO FIRE WEATHER PROBLEMS ARE ANTICIPATED THE NEXT FEW DAYS. HIGH PRESSURE WILL BUILD EASTWARD FROM THE GREAT LAKES REGION AND SOUTHEASTERN CANADA ACROSS THE NORTHEAST TODAY INTO SATURDAY...WITH COOLER TEMPERATURES AND COMFORTABLE HUMIDITY LEVELS. THE SURFACE ANTICYCLONE WILL DRIFT SOUTH AND EAST OF THE NORTHEAST ON SUNDAY WITH TEMPERATURES MODERATING SLIGHTLY ABOVE NORMAL WITH CONTINUED FAIR WEATHER. RELATIVE HUMIDITY VALUES WILL RECOVER TO 90 TO 100 PERCENT TONIGHT WITH SOME DEW FORMATION POSSIBLE. THE RH VALUES WILL FALL TO 30 TO 45 PERCENT SATURDAY AFTERNOON...THEN RECOVER TO 90-100 PERCENT FOR SAT NT WITH WIDESPREAD DEW FORMATION LIKELY. NORTH TO NORTHEAST WINDS AT 10-15 MPH WILL DECREASE TO 5-10 MPH OVERNIGHT. WINDS WILL BE NORTHEAST TO EAST AT 5-15 MPH SATURDAY...THEN BECOME LIGHT AND VARIABLE FOR SAT NT. && .HYDROLOGY... DRY WEATHER IS EXPECTED THROUGH THE WEEKEND. THE WEATHER BECOMES MORE UNSETTLED SUNDAY NIGHT INTO TUESDAY WITH ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS AS A LOW PRESSURE SYSTEM AND ITS ASSOCIATED FRONTAL BOUNDARIES APPROACHES FROM THE GREAT LAKES REGION. PRECIPITATION AMOUNTS WILL BE HIGHLY VARIABLE DEPENDING ON ANY CONVECTION. OVERALL FOR THE NEXT 5 DAYS...NO WIDESPREAD HYDRO PROBLEMS ARE EXPECTED. RIVER FLOWS...AND RESERVOIR LEVELS CONTINUE AT NORMAL TO SLIGHTLY BELOW NORMAL LEVELS FOR LATE AUGUST. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...KL/WASULA NEAR TERM...KL SHORT TERM...KL LONG TERM...LFM AVIATION...SND FIRE WEATHER...KL/WASULA HYDROLOGY...KL/WASULA
AREA FORECAST DISCUSSION
NWS NEW YORK NY
230 PM EDT FRI AUG 23 2013 .SYNOPSIS... A WEAK FRONTAL BOUNDARY WILL APPROACH FROM THE EAST THIS EVENING...AND PASS TO THE SOUTH TONIGHT. HIGH PRESSURE WILL THEN BUILD IN THIS WEEKEND...AND SETTLE TO THE SOUTH EARLY NEXT WEEK. MULTIPLE LOWS WILL IMPACT THE NORTHEAST NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... HIGH CLOUD DEBRIS FROM MID ATLANTIC MCS HAS DRIFTED IN...MAKING FOR WITH A PTCLDY AFTERNOON AND EVENING. MEANWHILE...SUBTLE FRONTAL BOUNDARY/CONVERGENCE ZONE IS MOVING IN FROM THE EAST... MARKED ATTM BY CLOUD LINE CUTTING NE-SW ACROSS RHODE ISLAND... WITH NE FLOW ON THE COOL EAST SIDE OF THE BOUNDARY. THE BOUNDARY SHOULD GRADUALLY DRIFT SW INTO THE AREA...WITH HRRR SHOWING POTENTIAL FOR A FEW SHOWERS OVER FAR ERN CT/LONG ISLAND. HRRR IS USUALLY TOO QUICK TO INITIATE CONVECTION SO INTRODUCED SLIGHT CHANCE POP FOR THESE AREAS INTO THIS EVENING RATHER THAN LATE AFTERNOON. BOUNDARY COULD SPARK A FEW ADDITIONAL SHOWERS TONIGHT...BUT THINK THESE WILL BE MAINLY OVER THE OCEAN AND IN TANDEM WITH A MID LEVEL SHORTWAVE TROUGH MOVING OHD TONIGHT. OTHERWISE...SKIES SHOULD BECOME MOSTLY CLEAR WITH DIMINISHING N-NE WINDS FOR MOST OF THE NIGHT...THEN PICKING UP A LITTLE TOWARD DAYBREAK ALONG THE COAST AS THE PRESSURE GRADIENT TIGHTENS BETWEEN HIGH PRESSURE BUILDING FROM THE NW AND LOW PRESSURE FORMING ALONG A FRONTAL ZONE SE OF CAPE COD. LOWS TONIGHT ARE A GUIDANCE BLEND...WITH 50S FOR INLAND SECTIONS...COASTAL SE CT AND THE LONG ISLAND PINE BARRENS...AND 60S ELSEWHERE. && .SHORT TERM /SATURDAY INTO SATURDAY NIGHT/... SUNNY AND MILD ON SAT AS NORTHERLY WINDS CONTINUE TO USHER IN SLIGHTLY COOLER AND DRIER AIR....WITH HIGHS 1-2 DEG EITHER SIDE OF 80. AS THE HIGH BUILDS TO THE NORTH...FLOW ALONG THE COAST SHOULD TURN E-SE IN THE AFTERNOON. COOLER SAT NIGHT WITH MOCLEAR SKIES AND LIGHT WINDS. LOWS WILL BE 60-65 IN NYC METRO...IN THE 50S MOST ELSEWHERE...AND 45-50 IN THE INTERIOR VALLEYS. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... A GENERALLY QUIET BEGINNING TO THE COMING WEEK...WITH INCREASING CHANCES OF ACTIVITY THROUGH THE WEEK WITH MULTIPLE SYSTEMS PASSING THROUGH. UPPER LEVEL PATTERN REMAINS FAIRLY CONSISTENT AS RIDGING SETS UP OVER THE CENTRAL US...KEEPING THE NORTHEAST REGION ON THE OUTER PERIPHERY OF THE RIDGE AND IN LINE FOR THE PASSING OF MULTIPLE SHORTWAVES. SUNDAY QUIET WITH THE CENTER OF THE SURFACE HIGH SITTING OHD AND SUBSIDENCE ALOFT PRODUCING MOSTLY CLEAR/SUNNY SKIES. INCREASING CLOUD COVERAGE SUNDAY NIGHT INTO MONDAY AS THE FIRST OF MANY SHORTWAVES ROUNDS THE RIDGE. BEGAN INTRODUCING POPS BY LATE AFTN MONDAY AS THE SURFACE HIGH SLIPS TO THE SOUTH AHEAD OF AN APPROACHING FRONTAL SYSTEM AND MORE PROMINENT SHORTWAVES ROUND THE RIDGE. SOME MODEL DIVERGENCE ON THE HANDLING OF THE LOW PRESSURE SYSTEM...HOW STRONG AND HOW QUICKLY IT PROGRESSES THROUGH AND WHETHER A SECONDARY LOW FORMS ALONG THE FRONT BY THURS. THE 00Z GFS/CMC HAVE A MORE PRONOUNCED LOW AND THE 00Z ECMWF A BIT QUICKER WITH THE INTRODUCTION OF PCPN MONDAY AS WELL AS LINGERING IT LONGER INTO MID WEEK WITH THE DEVELOPMENT OF THE SECOND LOW AND LINGERING IT OFF THE NE COAST. WITH SUCH DIFFERENCES IN THE MODELS AT THIS TIME...WILL MAINTAIN LOWER END CHC POPS MON NIGHT- WED...WITH DRYING CONDITIONS FOR NOW FOR THE END OF THE WEEK IN THE WAKE OF A PASSING COLD FRONT AND SUBSIDENCE ATTEMPTING TO BUILD IN ALOFT. ANY ACTIVITY THAT DOES DEVELOP EARLIER IN THE WEEK AT THE MOMENT LOOKS TO BE MORE SCATTERED IN NATURE. AFTER A WEEKEND OF NEAR NORMAL TEMPS...WAA WILL LEAD TO INCREASED TEMPS AND DEWPTS...RESULTING IN MORE HUMID CONDITIONS AND ABOVE NORMAL TEMPS. THIS WILL AID IN INCREASING THE INSTABILITY AS WELL...SO WILL KEEP MENTION OF THUNDER IN FOR THE FIRST HALF OF THE WEEK. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... HIGH PRESSURE BUILDS INTO THE TERMINALS THROUGH SATURDAY. VFR. A BRIEF SHOWER IS POSSIBLE 05Z TO 10Z IN THE VICINITY OF KJFK AND KISP. NORTHERLY WIND GRADUALLY BECOMES MORE NORTH TO NORTHEAST...020 TO 030...THIS AFTERNOON WITH ANY GUSTS SUBSIDING BY 22Z. WIND REMAINS NORTHEAST OVERNIGHT AND INTO SATURDAY AFTERNOON. NY METRO ENHANCED AVIATION WEATHER SUPPORT... DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN BE FOUND AT: HTTP://WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE) KEWR FCSTER COMMENTS: OCCASIONAL GUSTS UP TO 20 KT POSSIBLE THROUGH 21Z. KJFK FCSTER COMMENTS: OCCASIONAL GUSTS UP TO 20 KT POSSIBLE THROUGH 21Z. KLGA FCSTER COMMENTS: GUSTS TO AROUND 20 KT CONTINUE THROUGH 21Z. AN OCCASIONAL GUSTS TO 23Z WILL BE POSSIBLE. KTEB FCSTER COMMENTS: AN OCCASIONAL GUST TO AROUND 15 KT WILL BE POSSIBLE THROUGH 21Z. KHPN FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. KISP FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. OUTLOOK FOR 18Z SATURDAY THROUGH WEDNESDAY... .SATURDAY AFTERNOON-MONDAY...VFR. .MONDAY NIGHT-WEDNESDAY...SUB-VFR POSSIBLE IN SHRA/TSRA WITH LOW PRESSURE MOVING THROUGH THE AREA. && .MARINE... N FLOW SHOULD TURN E-NE THIS EVENING AS A WEAK FRONTAL BOUNDARY MOVES IN FROM THE EAST...AND THEN MORE NE LATE TONIGHT AS THE PRESSURE GRADIENT TIGHTENS BETWEEN HIGH PRESSURE BUILDING FROM THE NW AND LOW PRESSURE FORMING ALONG A FRONTAL ZONE SE OF CAPE COD. WIND GUSTS AND OCEAN SEAS SHOULD APPROACH BUT FALL SHY OF SCA CRITERIA OF 25 KT AND 5 FT LATE TONIGHT INTO EARLY SAT MORNING. OTHERWISE...QUIET THROUGH SAT NIGHT AS HIGH PRESSURE BUILDS IN. A WEAK PRESSURE GRADIENT RESULTING FROM HIGH PRESSURE KEEPS SUB- SCA CONDITIONS ON ALL WATERS TO END THE WEEKEND AND BEGIN THE COMING WEEK. POSSIBLE 5 FT SEAS ON THE OCEAN WATERS BY TUESDAY WITH PERSISTENT AND INCREASING SW FLOW AHEAD OF AN APPROACHING FRONTAL SYSTEM. SEAS ARE EXPECTED TO SUBSIDE BY WED AND SHOULD REMIND SUB-SCA THEN FOR THE REST OF THE WEEK. THUNDERSTORMS IN THE FIRST HALF OF THE WEEK MAY BRING SOME STRONGER GUSTS...BUT OTHERWISE WINDS SHOULD REMAIN BELOW 25 KT FOR THE PERIOD. && .HYDROLOGY... THERE IS SOME HEAVY RAIN POTENTIAL FOR NEXT WEEK. IT IS STILL TOO EARLY TO BE SPECIFIC ON EXACT TIMING/LOCATION. && .EQUIPMENT... DUE TO INTERFERENCE ISSUES WITH THE U.S. COAST GUARD...THE NEW YORK CITY NOAA ALL HAZARDS WEATHER RADIO STATION KWO35 HAS BEEN TEMPORARILY TAKEN OUT OF SERVICE WHILE A SOLUTION IS BEING FORMULATED. DURING THIS TIME...THE TRANSMITTER MAY BE RETURNED TO SERVICE INTERMITTENTLY FOR USE OF THE NOAA ALL HAZARDS RADIO PUBLIC WARNING SYSTEM DURING POTENTIALLY DANGEROUS WEATHER SITUATIONS...FOR ROUTINE WEEKLY TESTS OF THE WARNING SYSTEM...AND TO DETERMINE IF THE INTERFERENCE ISSUE HAS BEEN RESOLVED. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ SYNOPSIS...GOODMAN/MPS NEAR TERM...GOODMAN SHORT TERM...GOODMAN LONG TERM...SEARS AVIATION...MET MARINE...GOODMAN/MPS HYDROLOGY...GOODMAN/MPS EQUIPMENT...GOODMAN
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
1008 AM EDT Fri Aug 23 2013 ...LOCALLY HEAVY RAIN AND STORMY WEATHER EXPECTED LATER TODAY... .NEAR TERM [Rest of Today]... The large scale longwave pattern is highlighted by a broad ridge over Cntrl Conus with high over OK, flanked by troughs along the Pac and Atlc coasts (with base over N GA). Closer to home, weakening TUTT moving Wwd across w/Cntrl gulf and high just off SE FL coast. This places local area in a weakness between all these systems. At surface, high pressure remains in place with ridge from from high in Atlc east of N FL Wwd to high over FL Panhandle creating ELY flow. Looking Nwd, frontal boundary extends across Carolina and extreme Nrn GA. Looking SW, a tropical wave continues to move Wwd across W/Cntrl gulf. A weak MCV was noted just south of Pensacola moving Wwd with moist SELY flow in its wake. Latest radar pix show a fair amount of marine convection moving Nwd. During the rest of today, Ern mid/upper trough will dig Swd reaching N FL by tonight. This will displace high Swd and allow front to dip SWD. With digging trough and local area on back side of MCV, PWATS will remain above 2 inches. HI RES models like HRRR have a current good handle on weather which like yesterday shows marine convection moving Nwd overland by midday and proceeding Nwd reaching over Nrn tier counties during the mid-late aftn. The mean 1000-700mb flow will light from the SE so storms that develop will be slow movers with the potential for very heavy downpours. The combination of the digging front, approaching surface front and seabreeze- mesoscale interactions will favor strong to isold severe storms with damaging wind gusts. Toward sundown, focus will shift towards I-75 corridor and the merging of Gulf and east coast seabreeze. The main difference from yesterday is that lack of clouds will favor early diurnal heating with a better destabilization and strong to severe storms. This reflected in model soundings, i.e. RAP13 19Z TAE with Cpae 3134 j/kg and 2.20 inch PWAT. Will go with 70-40% S-N POP gradient. Max temps will once again be held below seasonal levels, mid 80s south to near 90 NE GA counties. && .SHORT TERM [Tonight through Sunday]... A backdoor "cold front" will translate slowly southward along the GA & Northeast FL coast this weekend, though any significant cooling and/or drying will remain well to our northeast. With ample deep layer moisture in place through the weekend, persistent, weak Q-G forcing associated with this front will maintain above-average rain chances across much of our forecast area, especially during the daytime hours over land (and overnight & morning hours over the coastal waters). The above-average cloud cover may help keep high temperatures a few degrees below climo. && .LONG TERM [Sunday Night through Thursday]... The long term period begins a bit of unsettled with a stalled frontal boundary across our southern CWA. Through the day on Sunday and into Monday deep layer ridging builds over the Plains, with surface high pressure advancing southwestward through the southeast US. A significantly drier air mass gets advected around the surface high pressure reducing PoPs around normal in our southern zones, and below normal for our northern zones. Any shower and thunderstorm activity through the period will primarily be driven by the afternoon sea breeze. && .AVIATION [Through 12Z Saturday]... VFR conditions are expected into the aftn hours. Scattered to numerous showers and thunderstorms are expected this afternoon spreading from the coast rest of this mornnig inland through the morning and into the afternoon. MVFR CIGS/VSBYS likely in any stronger storms and heavier rain. Will go with VCTS transitioning to TSRA ending during the eve from S-N. Then VFR returns until after 07z-08z with MVFR VSBYS and possibly CIGS except for IFR CIGS likely at VLD towards sunrise. && .MARINE... We are going on the assumption (backed by the agreement of the GFS and ECMWF) that the broad, weak low pressure trough (currently in the north central Gulf of Mexico) will not intensify significantly, keeping our local pressure gradient fairly "loose". This means east winds generally less than 15 KT and seas less than 4 feet. && .FIRE WEATHER... No fire weather concerns. && .HYDROLOGY... With Precip Water values continuing above average and Flash Flood Guidance still below average, we still have to think about any potential for flash flooding. Fortunately, the Convection Allowing Models (CAM) consensus doesn`t forecast much in the way of sustained, organized convection today. So although rainfall rates could be very high (3-4 inches/hour), the expected lack of organization makes issuing a watch unnecessary at this time. If flooding occurs, it would most likely be limited to urban areas and/or low-lying areas that already have standing water. Several of our local rivers continued with high flows/stages, mainly in the lower portions of the basins. Of these, the Chipola River at Altha, Choctawhatchee River at Bruce, and Ochlockonee River at Concord and Havana were at moderate flood stage or higher. Please refer to our web page for details, under the "Rivers & Lakes" tab. && .PRELIMINARY POINT TEMPS/POPS... Tallahassee 88 71 89 71 89 / 70 30 50 30 40 Panama City 85 75 87 76 86 / 70 40 50 30 40 Dothan 87 72 88 72 89 / 50 20 40 30 30 Albany 90 72 91 72 89 / 50 20 40 30 30 Valdosta 89 72 89 70 88 / 60 20 50 30 40 Cross City 88 73 88 72 88 / 70 30 50 30 40 Apalachicola 85 75 86 77 86 / 70 40 50 30 40 && .TAE WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AL...None. GM...None. && $$ NEAR TERM/Aviation/Marine...Block SHORT TERM...Fournier LONG TERM...Navarro/DVD FIRE WEATHER...Barry HYDROLOGY...Fournier
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
150 PM EDT FRI AUG 23 2013 .PREV DISCUSSION... /ISSUED 1128 AM EDT FRI AUG 23 2013/ UPDATE... HAVE MADE SEVERAL MAINLY MINOR TWEAKS TO GRIDS THIS MORNING... MAINLY TO UPDATE TRENDS. DID REDUCE POPS FOR THE MORNING AND EARLY AFTERNOON HOURS BUT EXCEPT FOR SENDING THE NEW GRIDS TO THE WEB... NO UPDATED PRODUCTS NECESSARY WITH THAT SINCE AFTERNOON POPS REMAIN THE SAME. AS CONVECTION FIRES...MAY HAVE TO REEVALUATE LOCATION OF HIGHEST POPS THROUGH THE AFTERNOON BUT FOR THE MOST PART GRIDS LOOK GOOD. NO UPDATE PLANNED. TDP PREV DISCUSSION... /ISSUED 748 AM EDT FRI AUG 23 2013/ PREV DISCUSSION... /ISSUED 348 AM EDT FRI AUG 23 2013/ SHORT TERM /TODAY THROUGH SATURDAY/... LATEST SOUTHEAST SURFACE ANALYSIS SHOWS FRONTAL BOUNDARY EXTENDING FROM THE EASTERN CAROLINAS THROUGH EXTREME SOUTH GEORGIA WITH WEAK RIDGING ACROSS THE TENNESSEE VALLEY INTO NORTH GEORGIA. A STRONGER FRONT IS NOTED TO THE NORTH AS HIGH PRESSURE MOVES INTO THE GREAT LAKES REGION AND DRIVES FRONT INTO THE OHIO VALLEY AND PORTIONS OF THE APPALACHIANS. ALTHOUGH NOT COMPLETELY DRY...WATER VAPOR IMAGERY DOES SHOW SLOT OF DRIER AIR OVER NORTH GEORGIA WHICH ALONG WITH A LACK OF MID LEVEL FORCING HAS ALLOWED FOR TRANQUIL OVERNIGHT CONDITIONS. WILL NEED TO WATCH CLOSELY TOWARD DAYBREAK AS NAM12 CONDENSATION PRESSURE DEFICIT ANALYSIS INDICATES A GOOD CHANCE OF FOG AND LOW CIGS OVER PORTIONS OF NORTH GEORGIA INCLUDING THE NORTHERN METRO AND A SEPARATE BATCH COMING UP FROM THE SOUTH LATE. HAVE ADDED PATCHY FOG TO GRIDS TO COVER FOR NOW BUT THIS COVERAGE OR INTENSITY MAY NEED TO BE INCREASED. FOR TODAY...BASED SOLELY ON AVAILABLE MOISTURE AND UTILIZING PWAT FORECAST...SOUTHERN SECTIONS SHOULD SEE THE BEST CHANCES THIS AFTERNOON. HOWEVER...WRF AND HRRR AS WELL AS SOME OTHER SHORT TERM MODELS POINT TO SECONDARY DEVELOPMENT LATE AS SHORTWAVE ENERGY DIVES INTO THE NORTHERN SECTIONS. TRIED TO ACCOUNT FOR BOTH PROJECTIONS WITH HIGHER POPS SOUTH AND NORTH WITH LOWER POPS IN THE MIDDLE COVERING THE ATLANTA METRO. CAPES GENERALLY AROUND 2000 J/KG TO 3000 J/KG WILL BE POSSIBLE WHICH WILL BE SUFFICIENT TO FUEL ISOLATED STRONG THUNDERSTORMS. DCAPE LOOKS TO REMAIN BELOW 1000 J/KG BUT ENOUGH PRECIPITATION LOADING WILL BE PRESENT TO ALLOW FOR MICROBURST POTENTIAL. MORE STORM MOTION TODAY BY A COUPLE OF KNOTS BUT FEEL BOUNDARY COLLISIONS ALONG WITH LOW FFG VALUES COULD STILL LEAD TO ISOLATED FLASH FLOODING ACROSS THE AREA. OHIO VALLEY HIGH PRESSURE BRIDGES ACROSS THE NORTHEAST STATES WITH RIDGING AND SUBTLE EDGE FEATURE THROUGH THE CAROLINAS AND GEORGIA. ADDITIONAL DRY AIR SHOULD KEEP FOCUS OF HIGHEST POPS FOR THE SOUTHERN SECTIONS...EXCEPT NORTHEAST MOUNTAINS WHERE NAMDNG5 SHOWS ENHANCED DEVELOPMENT DURING THE AFTERNOON. DEESE LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... A COLD FRONT IS FORECAST TO MOVE S OF THE AREA SATURDAY EVENING AS SURFACE HIGH PRESSURE BUILDS ALONG THE EASTERN SEABOARD AND UPPER LEVEL HIGH PRESSURE BUILDS OVER THE MID U.S. SHOWER AND THUNDERSTORM CHANCES SHOULD BE HIGHLY DIURNAL SATURDAY NIGHT AND DIMINISH WITH THE LOSS OF HEATING. SHOWER AND THUNDERSTORM CHANCES LOOK TO BE LIMITED TO MAINLY CENTRAL GA ON SUNDAY DURING THE AFTERNOON AND EARLY EVENING HOURS WHERE THE BEST INSTABILITY IS EXPECTED TO BE WITH THE INFLUENCE OF DRIER AIR AND HIGH PRESSURE HAVING THE MOST AFFECT ON N GA. PRECIP CHANCES FOR MONDAY AND TUESDAY LOOK TO BE AS LOW AS WE HAVE SEEN IN A LONG TIME WITH A GENERALLY DRIER AIRMASS OVER THE AREA AND THE INFLUENCE OF HIGH PRESSURE. GFS IS MORE AGGRESSIVE WITH PRECIP AMOUNTS AND CHANCES THAN THE EUROPEAN. WILL NEED TO WATCH THE NE MOUNTAINS AND FAR S AS AREAS WHERE SMALL CHANCES COULD BE NEEDED. GFS MORE AGGRESSIVE WITH MOISTURE RETURN ON WEDNESDAY THAN THE EUROPEAN FROM THE NNW FLOW ALOFT. GUIDANCE FROM HPC FAVORING LOW POPS FOR N AND PORTIONS OF CENTRAL GA. A SURFACE TROUGH DEVELOPS ACROSS THE AREA ON THURSDAY AND AGAIN THE GFS IS MORE AGGRESSIVE WITH THE MOISTURE THAN THE EUROPEAN IN THE NNW FLOW ALOFT. HPC GUIDANCE FAVORING LOW POPS ACROSS THE ENTIRE AREA DUE TO THE UNCERTAINTY. BOTH MODELS INDICATING INCREASED MOISTURE OVER THE AREA ON FRIDAY. TEMPERATURES GENERALLY RUNNING NEAR TO AROUND 6 DEGREES BELOW NORMAL DURING THIS PERIOD. BDL && .AVIATION... 18Z UPDATE... VFR EVERYWHERE THIS AFTERNOON. HAVE KEPT FORMER PROB30 TIMING AND JUST CHANGED TO TEMPO AT ATL...WILL MONITOR FOR OTHER SITES. EXPECT MVFR FOG TO DEVELOP AGAIN IN THE MORNING WITH WIND SHIFT TO NE AFTER 06Z. MAY SEE LOWER CONDITIONS AGAIN AT MCN LIKE THIS MORNING. CLEARING AFTER 14Z. ADDED ANOTHER PROB30 FOR ATL SATURDAY AFTERNOON. //ATL CONFIDENCE...18Z UPDATE... MEDIUM ON AFTERNOON CONVECTION. MEDIUM ON VSBY SATURDAY MORNING. HIGH ON ALL OTHER ELEMENTS. TDP && .PRELIMINARY POINT TEMPS/POPS... ATHENS 91 73 84 67 / 40 30 30 20 ATLANTA 89 75 86 70 / 40 20 30 20 BLAIRSVILLE 86 67 81 65 / 50 20 30 10 CARTERSVILLE 90 72 87 69 / 30 20 20 20 COLUMBUS 90 77 88 72 / 50 30 30 20 GAINESVILLE 88 73 83 69 / 40 20 30 20 MACON 91 74 87 71 / 50 30 30 20 ROME 91 72 87 69 / 40 20 20 20 PEACHTREE CITY 88 72 85 69 / 40 20 30 20 VIDALIA 89 75 88 71 / 50 30 40 20 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
1128 AM EDT FRI AUG 23 2013 .UPDATE... HAVE MADE SEVERAL MAINLY MINOR TWEAKS TO GRIDS THIS MORNING... MAINLY TO UPDATE TRENDS. DID REDUCE POPS FOR THE MORNING AND EARLY AFTERNOON HOURS BUT EXCEPT FOR SENDING THE NEW GRIDS TO THE WEB... NO UPDATED PRODUCTS NECESSARY WITH THAT SINCE AFTERNOON POPS REMAIN THE SAME. AS CONVECTION FIRES...MAY HAVE TO REEVALUATE LOCATION OF HIGHEST POPS THROUGH THE AFTERNOON BUT FOR THE MOST PART GRIDS LOOK GOOD. NO UPDATE PLANNED. TDP && .PREV DISCUSSION... /ISSUED 748 AM EDT FRI AUG 23 2013/ PREV DISCUSSION... /ISSUED 348 AM EDT FRI AUG 23 2013/ SHORT TERM /TODAY THROUGH SATURDAY/... LATEST SOUTHEAST SURFACE ANALYSIS SHOWS FRONTAL BOUNDARY EXTENDING FROM THE EASTERN CAROLINAS THROUGH EXTREME SOUTH GEORGIA WITH WEAK RIDGING ACROSS THE TENNESSEE VALLEY INTO NORTH GEORGIA. A STRONGER FRONT IS NOTED TO THE NORTH AS HIGH PRESSURE MOVES INTO THE GREAT LAKES REGION AND DRIVES FRONT INTO THE OHIO VALLEY AND PORTIONS OF THE APPALACHIANS. ALTHOUGH NOT COMPLETELY DRY...WATER VAPOR IMAGERY DOES SHOW SLOT OF DRIER AIR OVER NORTH GEORGIA WHICH ALONG WITH A LACK OF MID LEVEL FORCING HAS ALLOWED FOR TRANQUIL OVERNIGHT CONDITIONS. WILL NEED TO WATCH CLOSELY TOWARD DAYBREAK AS NAM12 CONDENSATION PRESSURE DEFICIT ANALYSIS INDICATES A GOOD CHANCE OF FOG AND LOW CIGS OVER PORTIONS OF NORTH GEORGIA INCLUDING THE NORTHERN METRO AND A SEPARATE BATCH COMING UP FROM THE SOUTH LATE. HAVE ADDED PATCHY FOG TO GRIDS TO COVER FOR NOW BUT THIS COVERAGE OR INTENSITY MAY NEED TO BE INCREASED. FOR TODAY...BASED SOLELY ON AVAILABLE MOISTURE AND UTILIZING PWAT FORECAST...SOUTHERN SECTIONS SHOULD SEE THE BEST CHANCES THIS AFTERNOON. HOWEVER...WRF AND HRRR AS WELL AS SOME OTHER SHORT TERM MODELS POINT TO SECONDARY DEVELOPMENT LATE AS SHORTWAVE ENERGY DIVES INTO THE NORTHERN SECTIONS. TRIED TO ACCOUNT FOR BOTH PROJECTIONS WITH HIGHER POPS SOUTH AND NORTH WITH LOWER POPS IN THE MIDDLE COVERING THE ATLANTA METRO. CAPES GENERALLY AROUND 2000 J/KG TO 3000 J/KG WILL BE POSSIBLE WHICH WILL BE SUFFICIENT TO FUEL ISOLATED STRONG THUNDERSTORMS. DCAPE LOOKS TO REMAIN BELOW 1000 J/KG BUT ENOUGH PRECIPITATION LOADING WILL BE PRESENT TO ALLOW FOR MICROBURST POTENTIAL. MORE STORM MOTION TODAY BY A COUPLE OF KNOTS BUT FEEL BOUNDARY COLLISIONS ALONG WITH LOW FFG VALUES COULD STILL LEAD TO ISOLATED FLASH FLOODING ACROSS THE AREA. OHIO VALLEY HIGH PRESSURE BRIDGES ACROSS THE NORTHEAST STATES WITH RIDGING AND SUBTLE EDGE FEATURE THROUGH THE CAROLINAS AND GEORGIA. ADDITIONAL DRY AIR SHOULD KEEP FOCUS OF HIGHEST POPS FOR THE SOUTHERN SECTIONS...EXCEPT NORTHEAST MOUNTAINS WHERE NAMDNG5 SHOWS ENHANCED DEVELOPMENT DURING THE AFTERNOON. DEESE LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... A COLD FRONT IS FORECAST TO MOVE S OF THE AREA SATURDAY EVENING AS SURFACE HIGH PRESSURE BUILDS ALONG THE EASTERN SEABOARD AND UPPER LEVEL HIGH PRESSURE BUILDS OVER THE MID U.S. SHOWER AND THUNDERSTORM CHANCES SHOULD BE HIGHLY DIURNAL SATURDAY NIGHT AND DIMINISH WITH THE LOSS OF HEATING. SHOWER AND THUNDERSTORM CHANCES LOOK TO BE LIMITED TO MAINLY CENTRAL GA ON SUNDAY DURING THE AFTERNOON AND EARLY EVENING HOURS WHERE THE BEST INSTABILITY IS EXPECTED TO BE WITH THE INFLUENCE OF DRIER AIR AND HIGH PRESSURE HAVING THE MOST AFFECT ON N GA. PRECIP CHANCES FOR MONDAY AND TUESDAY LOOK TO BE AS LOW AS WE HAVE SEEN IN A LONG TIME WITH A GENERALLY DRIER AIRMASS OVER THE AREA AND THE INFLUENCE OF HIGH PRESSURE. GFS IS MORE AGGRESSIVE WITH PRECIP AMOUNTS AND CHANCES THAN THE EUROPEAN. WILL NEED TO WATCH THE NE MOUNTAINS AND FAR S AS AREAS WHERE SMALL CHANCES COULD BE NEEDED. GFS MORE AGGRESSIVE WITH MOISTURE RETURN ON WEDNESDAY THAN THE EUROPEAN FROM THE NNW FLOW ALOFT. GUIDANCE FROM HPC FAVORING LOW POPS FOR N AND PORTIONS OF CENTRAL GA. A SURFACE TROUGH DEVELOPS ACROSS THE AREA ON THURSDAY AND AGAIN THE GFS IS MORE AGGRESSIVE WITH THE MOISTURE THAN THE EUROPEAN IN THE NNW FLOW ALOFT. HPC GUIDANCE FAVORING LOW POPS ACROSS THE ENTIRE AREA DUE TO THE UNCERTAINTY. BOTH MODELS INDICATING INCREASED MOISTURE OVER THE AREA ON FRIDAY. TEMPERATURES GENERALLY RUNNING NEAR TO AROUND 6 DEGREES BELOW NORMAL DURING THIS PERIOD. BDL AVIATION... 12Z UPDATE... FOG CONTINUES TO BUILD OVER CENTRAL GEORGIA AS WELL AS EXTREME NORTH GEORGIA BUT REMAINING OUTSIDE MOST ATL TERMINALS AT THIS TIME. WILL HOLD FOR NOW WITH VFR CONDITIONS. OTHERWISE...STILL EXPECTING SHRA AND TSRA DEVELOPMENT THIS AFTERNOON BUT REDUCED COVERAGE REQUIRING ONLY PROB30 AT THIS POINT. //ATL CONFIDENCE...12Z UPDATE... HIGH ON ALL ELEMENTS. DEESE && .PRELIMINARY POINT TEMPS/POPS... ATHENS 91 73 84 67 / 40 40 40 20 ATLANTA 89 75 86 70 / 40 40 40 20 BLAIRSVILLE 86 67 81 65 / 50 50 50 20 CARTERSVILLE 90 72 87 69 / 30 30 40 20 COLUMBUS 90 77 88 72 / 50 50 50 20 GAINESVILLE 88 73 83 69 / 40 40 40 20 MACON 91 74 87 71 / 50 50 50 20 ROME 91 72 87 69 / 40 40 40 20 PEACHTREE CITY 88 72 85 69 / 40 40 40 20 VIDALIA 89 75 88 71 / 50 50 50 20 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
748 AM EDT FRI AUG 23 2013 .PREV DISCUSSION... /ISSUED 348 AM EDT FRI AUG 23 2013/ SHORT TERM /TODAY THROUGH SATURDAY/... LATEST SOUTHEAST SURFACE ANALYSIS SHOWS FRONTAL BOUNDARY EXTENDING FROM THE EASTERN CAROLINAS THROUGH EXTREME SOUTH GEORGIA WITH WEAK RIDGING ACROSS THE TENNESSEE VALLEY INTO NORTH GEORGIA. A STRONGER FRONT IS NOTED TO THE NORTH AS HIGH PRESSURE MOVES INTO THE GREAT LAKES REGION AND DRIVES FRONT INTO THE OHIO VALLEY AND PORTIONS OF THE APPALACHIANS. ALTHOUGH NOT COMPLETELY DRY...WATER VAPOR IMAGERY DOES SHOW SLOT OF DRIER AIR OVER NORTH GEORGIA WHICH ALONG WITH A LACK OF MID LEVEL FORCING HAS ALLOWED FOR TRANQUIL OVERNIGHT CONDITIONS. WILL NEED TO WATCH CLOSELY TOWARD DAYBREAK AS NAM12 CONDENSATION PRESSURE DEFICIT ANALYSIS INDICATES A GOOD CHANCE OF FOG AND LOW CIGS OVER PORTIONS OF NORTH GEORGIA INCLUDING THE NORTHERN METRO AND A SEPARATE BATCH COMING UP FROM THE SOUTH LATE. HAVE ADDED PATCHY FOG TO GRIDS TO COVER FOR NOW BUT THIS COVERAGE OR INTENSITY MAY NEED TO BE INCREASED. FOR TODAY...BASED SOLELY ON AVAILABLE MOISTURE AND UTILIZING PWAT FORECAST...SOUTHERN SECTIONS SHOULD SEE THE BEST CHANCES THIS AFTERNOON. HOWEVER...WRF AND HRRR AS WELL AS SOME OTHER SHORT TERM MODELS POINT TO SECONDARY DEVELOPMENT LATE AS SHORTWAVE ENERGY DIVES INTO THE NORTHERN SECTIONS. TRIED TO ACCOUNT FOR BOTH PROJECTIONS WITH HIGHER POPS SOUTH AND NORTH WITH LOWER POPS IN THE MIDDLE COVERING THE ATLANTA METRO. CAPES GENERALLY AROUND 2000 J/KG TO 3000 J/KG WILL BE POSSIBLE WHICH WILL BE SUFFICIENT TO FUEL ISOLATED STRONG THUNDERSTORMS. DCAPE LOOKS TO REMAIN BELOW 1000 J/KG BUT ENOUGH PRECIPITATION LOADING WILL BE PRESENT TO ALLOW FOR MICROBURST POTENTIAL. MORE STORM MOTION TODAY BY A COUPLE OF KNOTS BUT FEEL BOUNDARY COLLISIONS ALONG WITH LOW FFG VALUES COULD STILL LEAD TO ISOLATED FLASH FLOODING ACROSS THE AREA. OHIO VALLEY HIGH PRESSURE BRIDGES ACROSS THE NORTHEAST STATES WITH RIDGING AND SUBTLE EDGE FEATURE THROUGH THE CAROLINAS AND GEORGIA. ADDITIONAL DRY AIR SHOULD KEEP FOCUS OF HIGHEST POPS FOR THE SOUTHERN SECTIONS...EXCEPT NORTHEAST MOUNTAINS WHERE NAMDNG5 SHOWS ENHANCED DEVELOPMENT DURING THE AFTERNOON. DEESE LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... A COLD FRONT IS FORECAST TO MOVE S OF THE AREA SATURDAY EVENING AS SURFACE HIGH PRESSURE BUILDS ALONG THE EASTERN SEABOARD AND UPPER LEVEL HIGH PRESSURE BUILDS OVER THE MID U.S. SHOWER AND THUNDERSTORM CHANCES SHOULD BE HIGHLY DIURNAL SATURDAY NIGHT AND DIMINISH WITH THE LOSS OF HEATING. SHOWER AND THUNDERSTORM CHANCES LOOK TO BE LIMITED TO MAINLY CENTRAL GA ON SUNDAY DURING THE AFTERNOON AND EARLY EVENING HOURS WHERE THE BEST INSTABILITY IS EXPECTED TO BE WITH THE INFLUENCE OF DRIER AIR AND HIGH PRESSURE HAVING THE MOST AFFECT ON N GA. PRECIP CHANCES FOR MONDAY AND TUESDAY LOOK TO BE AS LOW AS WE HAVE SEEN IN A LONG TIME WITH A GENERALLY DRIER AIRMASS OVER THE AREA AND THE INFLUENCE OF HIGH PRESSURE. GFS IS MORE AGGRESSIVE WITH PRECIP AMOUNTS AND CHANCES THAN THE EUROPEAN. WILL NEED TO WATCH THE NE MOUNTAINS AND FAR S AS AREAS WHERE SMALL CHANCES COULD BE NEEDED. GFS MORE AGGRESSIVE WITH MOISTURE RETURN ON WEDNESDAY THAN THE EUROPEAN FROM THE NNW FLOW ALOFT. GUIDANCE FROM HPC FAVORING LOW POPS FOR N AND PORTIONS OF CENTRAL GA. A SURFACE TROUGH DEVELOPS ACROSS THE AREA ON THURSDAY AND AGAIN THE GFS IS MORE AGGRESSIVE WITH THE MOISTURE THAN THE EUROPEAN IN THE NNW FLOW ALOFT. HPC GUIDANCE FAVORING LOW POPS ACROSS THE ENTIRE AREA DUE TO THE UNCERTAINTY. BOTH MODELS INDICATING INCREASED MOISTURE OVER THE AREA ON FRIDAY. TEMPERATURES GENERALLY RUNNING NEAR TO AROUND 6 DEGREES BELOW NORMAL DURING THIS PERIOD. BDL .AVIATION... 12Z UPDATE... FOG CONTINUES TO BUILD OVER CENTRAL GEORGIA AS WELL AS EXTREME NORTH GEORGIA BUT REMAINING OUTSIDE MOST ATL TERMINALS AT THIS TIME. WILL HOLD FOR NOW WITH VFR CONDITIONS. OTHERWISE...STILL EXPECTING SHRA AND TSRA DEVELOPMENT THIS AFTERNOON BUT REDUCED COVERAGE REQUIRING ONLY PROB30 AT THIS POINT. //ATL CONFIDENCE...12Z UPDATE... HIGH ON ALL ELEMENTS. DEESE && .PRELIMINARY POINT TEMPS/POPS... ATHENS 91 73 84 67 / 40 40 40 20 ATLANTA 89 75 86 70 / 40 40 40 20 BLAIRSVILLE 86 67 81 65 / 50 50 50 20 CARTERSVILLE 90 72 87 69 / 30 30 40 20 COLUMBUS 90 77 88 72 / 50 50 50 20 GAINESVILLE 88 73 83 69 / 40 40 40 20 MACON 91 74 87 71 / 50 50 50 20 ROME 91 72 87 69 / 40 40 40 20 PEACHTREE CITY 88 72 85 69 / 40 40 40 20 VIDALIA 89 75 88 71 / 50 50 50 20 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...DEESE LONG TERM....BDL AVIATION...DEESE
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
348 AM EDT FRI AUG 23 2013 .SHORT TERM /TODAY THROUGH SATURDAY/... LATEST SOUTHEAST SURFACE ANALYSIS SHOWS FRONTAL BOUNDARY EXTENDING FROM THE EASTERN CAROLINAS THROUGH EXTREME SOUTH GEORGIA WITH WEAK RIDGING ACROSS THE TENNESSEE VALLEY INTO NORTH GEORGIA. A STRONGER FRONT IS NOTED TO THE NORTH AS HIGH PRESSURE MOVES INTO THE GREAT LAKES REGION AND DRIVES FRONT INTO THE OHIO VALLEY AND PORTIONS OF THE APPALACHIANS. ALTHOUGH NOT COMPLETELY DRY...WATER VAPOR IMAGERY DOES SHOW SLOT OF DRIER AIR OVER NORTH GEORGIA WHICH ALONG WITH A LACK OF MID LEVEL FORCING HAS ALLOWED FOR TRANQUIL OVERNIGHT CONDITIONS. WILL NEED TO WATCH CLOSELY TOWARD DAYBREAK AS NAM12 CONDENSATION PRESSURE DEFICIT ANALYSIS INDICATES A GOOD CHANCE OF FOG AND LOW CIGS OVER PORTIONS OF NORTH GEORGIA INCLUDING THE NORTHERN METRO AND A SEPARATE BATCH COMING UP FROM THE SOUTH LATE. HAVE ADDED PATCHY FOG TO GRIDS TO COVER FOR NOW BUT THIS COVERAGE OR INTENSITY MAY NEED TO BE INCREASED. FOR TODAY...BASED SOLELY ON AVAILABLE MOISTURE AND UTILIZING PWAT FORECAST...SOUTHERN SECTIONS SHOULD SEE THE BEST CHANCES THIS AFTERNOON. HOWEVER...WRF AND HRRR AS WELL AS SOME OTHER SHORT TERM MODELS POINT TO SECONDARY DEVELOPMENT LATE AS SHORTWAVE ENERGY DIVES INTO THE NORTHERN SECTIONS. TRIED TO ACCOUNT FOR BOTH PROJECTIONS WITH HIGHER POPS SOUTH AND NORTH WITH LOWER POPS IN THE MIDDLE COVERING THE ATLANTA METRO. CAPES GENERALLY AROUND 2000 J/KG TO 3000 J/KG WILL BE POSSIBLE WHICH WILL BE SUFFICIENT TO FUEL ISOLATED STRONG THUNDERSTORMS. DCAPE LOOKS TO REMAIN BELOW 1000 J/KG BUT ENOUGH PRECIPITATION LOADING WILL BE PRESENT TO ALLOW FOR MICROBURST POTENTIAL. MORE STORM MOTION TODAY BY A COUPLE OF KNOTS BUT FEEL BOUNDARY COLLISIONS ALONG WITH LOW FFG VALUES COULD STILL LEAD TO ISOLATED FLASH FLOODING ACROSS THE AREA. OHIO VALLEY HIGH PRESSURE BRIDGES ACROSS THE NORTHEAST STATES WITH RIDGING AND SUBTLE EDGE FEATURE THROUGH THE CAROLINAS AND GEORGIA. ADDITIONAL DRY AIR SHOULD KEEP FOCUS OF HIGHEST POPS FOR THE SOUTHERN SECTIONS...EXCEPT NORTHEAST MOUNTAINS WHERE NAMDNG5 SHOWS ENHANCED DEVELOPMENT DURING THE AFTERNOON. DEESE .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... A COLD FRONT IS FORECAST TO MOVE S OF THE AREA SATURDAY EVENING AS SURFACE HIGH PRESSURE BUILDS ALONG THE EASTERN SEABOARD AND UPPER LEVEL HIGH PRESSURE BUILDS OVER THE MID U.S. SHOWER AND THUNDERSTORM CHANCES SHOULD BE HIGHLY DIURNAL SATURDAY NIGHT AND DIMINISH WITH THE LOSS OF HEATING. SHOWER AND THUNDERSTORM CHANCES LOOK TO BE LIMITED TO MAINLY CENTRAL GA ON SUNDAY DURING THE AFTERNOON AND EARLY EVENING HOURS WHERE THE BEST INSTABILITY IS EXPECTED TO BE WITH THE INFLUENCE OF DRIER AIR AND HIGH PRESSURE HAVING THE MOST AFFECT ON N GA. PRECIP CHANCES FOR MONDAY AND TUESDAY LOOK TO BE AS LOW AS WE HAVE SEEN IN A LONG TIME WITH A GENERALLY DRIER AIRMASS OVER THE AREA AND THE INFLUENCE OF HIGH PRESSURE. GFS IS MORE AGGRESSIVE WITH PRECIP AMOUNTS AND CHANCES THAN THE EUROPEAN. WILL NEED TO WATCH THE NE MOUNTAINS AND FAR S AS AREAS WHERE SMALL CHANCES COULD BE NEEDED. GFS MORE AGGRESSIVE WITH MOISTURE RETURN ON WEDNESDAY THAN THE EUROPEAN FROM THE NNW FLOW ALOFT. GUIDANCE FROM HPC FAVORING LOW POPS FOR N AND PORTIONS OF CENTRAL GA. A SURFACE TROUGH DEVELOPS ACROSS THE AREA ON THURSDAY AND AGAIN THE GFS IS MORE AGGRESSIVE WITH THE MOISTURE THAN THE EUROPEAN IN THE NNW FLOW ALOFT. HPC GUIDANCE FAVORING LOW POPS ACROSS THE ENTIRE AREA DUE TO THE UNCERTAINTY. BOTH MODELS INDICATING INCREASED MOISTURE OVER THE AREA ON FRIDAY. TEMPERATURES GENERALLY RUNNING NEAR TO AROUND 6 DEGREES BELOW NORMAL DURING THIS PERIOD. BDL && .AVIATION... 06Z UPDATE... MOISTURE PROFILES FROM VARIOUS MODEL PROJECTIONS SHOW BEST FOG CHANCES ACROSS EXTREME NORTH GA TO INCLUDE RYY AND PDK BUT REMAINING JUST OUTSIDE THE REMAINING ATL ARE TAF SITES. WILL BE A CLOSE CALL BUT WILL KEEP IFR OUT FOR NOW AND MONITOR CLOSELY THROUGH SUNRISE. ADDITIONAL LOW CLOUDS AND VSBY WILL BE POSSIBLE OVER THE SOUTHERN SECTIONS AS WELL TO INCLUDE MCN AND CSG. OTHERWISE...STILL EXPECTING SHRA AND TSRA DEVELOPMENT THIS AFTERNOON BUT REDUCED COVERAGE REQUIRING ONLY PROB30 AT THIS POINT. //ATL CONFIDENCE...06Z UPDATE... MEDIUM ON PRECIP TIMING AND EARLY MORNING VSBYS. HIGH ON REMAINING ELEMENTS. DEESE && .PRELIMINARY POINT TEMPS/POPS... ATHENS 91 73 84 67 / 40 40 40 20 ATLANTA 89 75 86 70 / 40 40 40 20 BLAIRSVILLE 86 67 81 65 / 50 50 50 20 CARTERSVILLE 90 72 87 69 / 30 30 40 20 COLUMBUS 90 77 88 72 / 50 50 50 20 GAINESVILLE 88 73 83 69 / 40 40 40 20 MACON 91 74 87 71 / 50 50 50 20 ROME 91 72 87 69 / 40 40 40 20 PEACHTREE CITY 88 72 85 69 / 40 40 40 20 VIDALIA 89 75 88 71 / 50 50 50 20 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...DEESE LONG TERM....BDL AVIATION...DEESE
AREA FORECAST DISCUSSION
NWS POCATELLO ID
852 PM MDT SAT AUG 24 2013 .UPDATE...STRONG THUNDERSTORMS FROM THIS AFTERNOON HAVE DECREASED IN INTENSITY WITH MAINLY ISOLATED CELLS IN EASTERN HIGHLANDS AND SCATTERED CELLS IN CENTRAL MOUNTAINS. SURFACE FRONTAL BOUNDARY STRETCHED THROUGH SNAKE PLAIN...WITH WINDS SOMEWHAT ENHANCED THIS EVENING BY OUTFLOW. SURFACE BOUNDARY SLOWLY PUSHES NORTH THROUGH REMAINDER OF TONIGHT. NAM CONTINUE TO INDICATE DRYING OVERNIGHT BUT RECENT HRR MAINTAINS CONVECTION OVER THE CENTRAL MOUNTAINS PAST MIDNIGHT...STRETCHING AREA OF SHOWERS/THUNDERSTORMS INTO THE NORTHEAST CORNER OF FORECAST AREA. ADDITIONALLY...WEAK SHOWERS PAINTED BY HRRR ALONG SOUTHERN EDGE OF FORECAST AREA AFTER MIDNIGHT AS WELL. WV IMAGERY SHOWS SURGE OF MOISTURE ASSOCIATED WITH SHORTWAVE MOVING QUICKLY NORTH THROUGH CENTRAL NEVADA THIS EVENING WHICH LENDS CREDENCE TO THESE IDEAS. THEREFORE LEFT WEAK POPS HIGHER ELEVATIONS MOST AREAS REMAINDER OF TONIGHT. HAVE MADE SOME MINOR ADJUSTMENTS FOR SAT/RADAR TRENDS WITH NO FURTHER UPDATES ANTICIPATED THIS EVENING. DMH && .PREV DISCUSSION... /ISSUED 207 PM MDT SAT AUG 24 2013/ SHORT TERM...FOR THIS AFTERNOON AND EVENING WATCHING THE DISTURBANCE IN SOUTHWEST FLOW CROSSING FROM CALIFORNIA INTO NEVADA. THERE IS ALSO A DISTURBANCE IN SOUTH CENTRAL AND EASTERN NEVADA MOVING NORTH WHERE LIGHTNING ACTIVITY HAS ALREADY BEGUN. CONVECTION SHOULD BEGIN EARLY THIS AFTERNOON BETWEEN OAKLEY AND SUN VALLEY. MODEL SOUNDINGS IN THAT AREA SHOWING HIGHER CAPE 1200-1300 J/KG THAN YESTERDAY WITH MODEST VERTICAL SHEAR THIS AFTERNOON TO SUPPORT STRONG CONVECTION. GOES SOUNDER INFORMATION HAS BEEN SHOWING UNSTABLE ENVIRONMENT PAST FEW HOURS. CONVECTION IN THE CARIBOU HIGHLANDS AREA COULD BE HELD BACK SOME AS THE UPPER LEVEL WINDS LEAVE THAT AREA IN CONVERGENCE ALOFT AND LESS SUPPORT FOR THUNDERSTORMS. SOUTHERLY BOUNDARY LAYER WINDS HAVE BEEN INCREASING FROM AROUND WENDOVER INTO THE BURLEY AREA THE NAM12 CONTINUES THIS TREND THROUGH WELL PAST MIDNIGHT. THEREFORE INCREASED MORNING LOW TEMPERATURES ALONG THE FOOT HILLS FROM BURLEY TO POCATELLO. THE INCREASED SOUTHERLY FLOW SHOULD ALSO ADD UPSLOPE FLOW TO SUPPORT SHOWERS IN THE UPPER SNAKE HIGHLANDS TONIGHT THAT MAY LAST PAST MIDNIGHT. SUNDAY...WATCHING TROPICAL STORM IVO OFF BAJA...MODELS BRING SOME OF THIS MOISTURE TOWARDS EVANSTON WYOMING BY SUNDAY AFTERNOON. WHILE SOME OF THIS MOISTURE WILL MISS THIS AREA...THE NAM12 SUGGEST A SPOKE OF ENERGY OFF THE CALIFORNIA COAST TROUGH WILL ACT TO PULL SOME OF THAT MOISTURE NORTH TOWARDS SUN VALLEY AREA SUNDAY AFTERNOON AND EVENING. INCREASED SHOWERS AND THUNDERSTORMS TO SCATTERED TOWARDS THAT AREA AND WE COULD SEE SOME .1 TO .2 INCH RAIN AMOUNTS FROM THUNDERSTORMS. LONG TERM...SOUTHEAST IDAHO REMAINS SQUEEZED IN THE FLOW BETWEEN THE HIGH CENTERED OVER KANSAS AND THE LOW OFF SHORE WITH MONSOON MOISTURE PROVIDING AN UNSTABLE AIR MASS THE NEXT FEW DAYS. THERE IS STILL A HINT OF ANOTHER TROPICAL WAVE CROSSING CENTRAL AMERICA BY FRIDAY. HOWEVER THE NORTHWARD SURGE OF MOISTURE INTO THE GREAT BASIN APPEARS MORE FRAGMENTED THAN SHOWN BY MODELS YESTERDAY. RS AVIATION...HAVE VICINITY THUNDERSTORMS ALL TAF SITES AGAIN THIS AFTERNOON THROUGH 04Z. THINK SUN MOST LIKELY SITE TO HAVE ON STATION TODAY. VFR CONDITIONS OUTSIDE THUNDERSTORMS. EXPECT SIMILAR CONDITIONS SUNDAY WITH ISOLATED TO SCATTERED STORMS ONCE AGAIN. GK FIRE WEATHER...SOUTHERLY FLOW ALOFT CONTINUES TO PUSH MOISTURE INTO SOUTHEAST IDAHO. RED FLAG WARNINGS REMAIN IN EFFECT UNTIL 10 PM THIS EVENING FOR SCATTERED THUNDERSTORMS. SOUTHERLY FLOW CONTINUES THROUGH MOST OF NEXT WEEK WITH ISOLATED TO SCATTERED THUNDERSTORMS EXPECTED DAILY THROUGH WEDNESDAY. MAY SEE LESS COVERAGE ON MONDAY WITH SOME DRIER AIR TEMPORARILY MOVING INTO THE REGION. GK && .PIH WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING UNTIL 10 PM MDT THIS EVENING IDZ410-413-422-425-427-475-476. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1256 PM CDT FRI AUG 23 2013 .DISCUSSION... 352 AM CDT SYNOPSIS...A LARGE RIDGE OVER THE CENTRAL US SPREADS EAST OVER THE GREAT LAKES. A WARMING TREND IS IN STORE THROUGH MID NEXT WEEK WITH HIGHS IN THE 90S AND HEAT INDICES IN THE 100S POSSIBLE. TODAY... HIGH PRESSURE IS OVER THE GREAT LAKES WITH A LARGE RIDGE ALOFT CENTERED OVER THE SOUTH CENTRAL GREAT PLAINS. PRIMARILY CLEAR SKIES OVERNIGHT COMBINED WITH WEAK TO CALM WINDS AND WET GROUND RESULTED IN AREAS TO WIDESPREAD DENSE FOG. HIGH LEVEL CIRRUS OVER THE EASTERN AND SOUTHERN PORTIONS OF THE CWA HAVE LIMITED FOG DEVELOPMENT A BIT AND RADIATIONAL COOLING. HOWEVER EXPECTING FOG TO BURN OFF QUICKLY THIS MORNING LEADING TO A DRY AND PLEASANT DAY WITH HIGHS IN THE LOW 80S. WINDS WILL BE OFF OF THE LAKE THEREFORE TEMPS WILL BE A FEW DEGREES COOLER ALONG THE LAKE FRONT BUT STILL BE IN THE UPPER 70S TO AROUND 80. REGARDING THE BEACH HAZARDS STATEMENT...THE NORTHEAST WINDS HAVE BEEN SLOW TO INCREASE BUT WILL THIS MORNING TO 10 TO 15 MPH ALONG THE LAKE SHORE AS THE SURFACE HIGH BUILDS SOUTHWARD. THE WAVE MAXIMUM AS DEPICTED BY OUR WAVE MODEL MOVES INTO THE COOK AND LAKE COUNTY INDIANA SHORELINE. WAVE HEIGHTS WILL BE A BIT MORE MARGINAL THAN ORIGINALLY THOUGHT...MAINLY 3 TO 4 FT BUT WAVE OCCASIONALLY TOPPING THAT ARE STILL EXPECTED. HAVE CANCELLED PORTER COUNTY FROM THE HEADLINE THOUGH GIVEN THE TRAJECTORY OF THE WAVE MAXIMUM. SATURDAY THROUGH MONDAY... THE UPPER LEVEL RIDGE EXPANDS OVER THE LOT CWA LATE TONIGHT INTO SATURDAY MORNING BUT REMAINS CENTERED OVER THE OZARKS/SOUTH CENTRAL PLAINS THROUGH THE REST OF THE FORECAST PERIOD. THE SURFACE HIGH PRESSURE CURRENTLY OVER THE GREAT LAKES SHIFTS EAST FRIDAY NIGHT INTO SUNDAY AND THEN SLIDES SOUTH BECOMING CENTERED OVER THE SOUTHEAST ATLANTIC COAST MONDAY NIGHT. MULTIPLE SHORTWAVES WILL ROTATE AROUND THE NORTHERN PORTION OF THE RIDGE WITH THE FIRST ONE SCOOTING NORTH OF THE CWA SATURDAY NIGHT. ADDITIONAL CONVECTION IS EXPECTED ACROSS NORTHERN WI...MI...AND THE NORTHERN HALF OF THE LAKE THROUGH SUNDAY NIGHT. CONVECTION SPREADS DOWN THE LENGTH OF THE LAKE MONDAY AS THE SURFACE HIGH SHIFTS SOUTH AND A BROAD SURFACE LOW OVER THE DAKOTAS SLOWLY SPREADS EAST. HOWEVER NOT ANTICIPATING ANY PRECIP OVER THE LAND PORTION OF THE LOT CWA. UPPER LEVEL TEMPS SLOWLY BUILD WITH 925MB TEMPS REACHING 24-28C ON MONDAY. LOCAL CLIMATOLOGY GUIDANCE SUGGESTS TEMPS SHOULD EASILY REACH THE LOW 90S ON MONDAY. FORECAST SOUNDINGS ALSO INDICATE DEWPOINTS MAY BE A BIT LOWER THAN CURRENTLY FORECAST DUE TO MIXING. THEREFORE KEPT DEWPOINTS A BIT LOWER THAN GUIDANCE WITH MAX HEAT INDICES IN THE UPPER 90S TO AROUND 100. LONG TERM...TUESDAY THROUGH THURSDAY... THE UPPER LEVEL RIDGE REMAINS IN PLACE THROUGH THE EXTENDED BUT A BROAD AREA OF LOW PRESSURE WEAKENS AS IT APPROACHES THE REGION. GUIDANCE IS STILL VERY FUZZY ON WHERE EXACTLY THIS LOW WILL TRACK AND HOW IT WILL IMPACT HIGH TEMPS THROUGH MID WEEK. FOR NOW STILL EXPECTING TEMPS TO CLIMB. 925MB TEMPS REACH 26-30C ALOFT AND EXPECTING THE PEAK OF THE HEAT TO BE TUESDAY AND WEDNESDAY WITH HIGH TEMPS IN THE LOW TO MID 90S. DEWPOINTS WILL BE AROUND 70 RESULTING IN HEAT INDICES AROUND 100-105F. WILL CONTINUE TO MONITOR MODEL TRENDS AS CLOUD COVER AND/OR THE WEAK LOW COULD LIMIT WARMING ON WEDNESDAY...BUT TUESDAY CERTAINLY LOOKS HOT. A WEAK BACKDOOR COLD FRONT MAY MOVE THROUGH THE REGION WEDNESDAY INTO THURSDAY WITH DRIER AND SLIGHTLY COOLER CONDITIONS EXPECTED. TEMPS LOOK LIKE THEY WILL BE IN THE LOW 90S BUT WITH DRIER CONDITIONS...HEAT INDICES IN THE MID TO UPPER 90S ARE EXPECTED. JEE && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * EAST TO NORTHEAST WINDS ARND 10-14KT THIS AFTERNOON DIMINISH ARND SUNSET TO 3-5KT. BEACHLER //DISCUSSION...UPDATED 18Z... HIGH PRESSURE OVERHEAD WILL CONTINUE TO PROVIDE OPTIMAL FLYING CONDITIONS TO NORTHERN IL/NORTHWEST IN AIRFIELDS. VISIBLE IMAGERY CONTINUES TO INDICATE NEAR CLOUDLESS SKIES FOR THE AREA AIRFIELDS...AND IS EXPECTED TO PERSIST OVERNIGHT INTO SATURDAY. EAST WINDS WITH SPEEDS GENERALLY AROUND 10-14KT WILL QUICKLY DIMINISH TO ARND 3-5KT OVERNIGHT...THEN BEGIN TO TURN SLIGHTLY TO THE SOUTHEAST. A FEW LOCATIONS COULD SEE SOME PATCHY GROUND FOG DEVELOP AGAIN OVERNIGHT...HOWEVER THIS SHOULD BE LIMITED AND NOT IMPACT THE TAF SITES. THEN AFTER DAYBREAK SATURDAY WINDS WILL SLOWLY INCREASE FROM THE SOUTHEAST/EAST TO ARND 10KT. BEACHLER //ORD AND MDW CONFIDENCE...UPDATED 18Z... * HIGH CONFIDENCE IN ALL FORECAST ELEMENTS. BEACHLER //OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z... SATURDAY NIGHT-MONDAY...VFR. TUESDAY-WEDNESDAY...VFR AND HOT DURING THE DAYS. SLIGHT CHC OF STORMS WED NIGHT. THURSDAY...VFR. MTF && .MARINE... 306 AM CDT HIGH PRESSURE WILL EXPAND ITS WAY DOWN THE LAKE TODAY LEADING TO NORTHEAST WINDS ACROSS NEARSHORE AREAS WHILE DIMINISHING WINDS OVER THE OPEN WATER. AS THE HIGH DEPARTS OFF TO THE EAST IT WILL STALL WITH BROAD LOW PRESSURE DEVELOPING OVER THE NORTHERN PLAINS. THIS PATTERN WILL PERSIST INTO NEXT WEEK MEANING PROLONGED SOUTHERLY FLOW OVER THE LAKE. SOME 30 KT GUSTS IN THE NORTH ON SUNDAY COULD BE SEEN. THIS OVERALL WEATHER PATTERN CAN AT TIMES LEAD TO A STRONG COMPLEX OR TWO OF STORMS FOR THE NORTHERN PART OF THE LAKE...AND THAT WOULD SEEM MOST FAVORED SOMETIME IN THE MON NIGHT-WED NIGHT TIME FRAME...THOUGH CONFIDENCE ON THIS REMAINS LOW. EVENTUALLY THE BROAD LOW WILL SHIFT OVER THE LAKE DURING THE MIDWEEK PERIOD. MTF && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion National Weather Service Lincoln IL 1216 PM CDT Fri Aug 23 2013 .DISCUSSION... ISSUED 949 AM CDT Fri Aug 23 2013 Areas of dense fog north of I-74 has been lifting into a stratus deck this morning, and should continue to thin from the edges over the next couple hours as diurnal mixing increases. Otherwise, high pressure north of Lake Superior will bring a 5-10 mph northeast wind flow to the region causing dewpoints will gradually fall into the low/mid 60s from north to south by late afternoon. Subsidence on the south side of the ridge should provide mostly sunny skies and seasonable highs in the mid 80s. && .AVIATION... ISSUED 1216 PM CDT Fri Aug 23 2013 High pressure over the northern Great Lakes will bring mostly clear skies and east winds under 10 kts to the terminals through 18z/Sat. MVFR fog will be possible within a few hours of sunrise. 25 && .PREV DISCUSSION... ISSUED 240 AM CDT Fri Aug 23 2013 SHORT TERM...Today through Saturday... Initial frontal passage has taken place over all of central and southeast Illinois early this morning, but drier air lingers a bit further back as lower 60s dew points now starting to enter the far northern CWA. A cluster of thunderstorms developed from Springfield to Decatur along the remnants of an old boundary from earlier, in an area with MUCAPE`s of around 1000 J/kg, and the cluster has been increasing a bit over the last hour or so as it moves south-southeast. Latest model guidance suggesting scattered showers/storms through about mid morning over about the southeast third of the forecast area. Further north, fog has been thickening and increasing over the northeast third of the state, where skies have cleared and the drier air has arrived. So far visibilities in our area have been staying up as a band of altocumulus has persisted, but clearing has been taking place from Galesburg to Lacon. However, the lower visibilities have been in areas that had quite a bit of rain on Thursday, and much of our forecast area had a quarter inch or less except in isolated spots. So, the question is how much of the forecast area, if any, will see dense fog this morning. HRRR guidance is the most pessimistic with it fairly widespread along and north of I-74, while the most recent RAP has scaled back and went mainly patchy dense fog in the same area. Currently have mention of 1/2 mile visibility in fog in this area through about 9 am, but will have to monitor for any significant advection from the northeast. Once the fog and rain moves out, quiet weather expected through the first part of the weekend. High pressure drifting through the Great Lakes will advect some drier air in from the east, but should still see highs in the mid-upper 80s. LONG TERM...Sunday through Thursday... Main weather story over the coming week continues to be with the expanding heat over the center of the nation, as a large dome of high pressure aloft drifts eastward. Any MCS ridge riders will be well to our north, and will continue the dry forecast for next week. Highs to rise through the 90s much of the week as thermal ridge builds eastward. Core of this ridge will be in the area on Wednesday. Latest ECMWF showing upper 90s over most of the forecast area that day. Have continued to trend temperatures up a degree or two from blended guidance with mid 90s widespread on Wednesday. Heat index values of just over 100 likely across the western CWA Monday-Tuesday and everywhere Wednesday. On Thursday, the thermal ridge starts shifting westward again, but should still see highs in the 93-95 range. Geelhart && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1114 AM CDT FRI AUG 23 2013 .DISCUSSION... 352 AM CDT SYNOPSIS...A LARGE RIDGE OVER THE CENTRAL US SPREADS EAST OVER THE GREAT LAKES. A WARMING TREND IS IN STORE THROUGH MID NEXT WEEK WITH HIGHS IN THE 90S AND HEAT INDICES IN THE 100S POSSIBLE. TODAY... HIGH PRESSURE IS OVER THE GREAT LAKES WITH A LARGE RIDGE ALOFT CENTERED OVER THE SOUTH CENTRAL GREAT PLAINS. PRIMARILY CLEAR SKIES OVERNIGHT COMBINED WITH WEAK TO CALM WINDS AND WET GROUND RESULTED IN AREAS TO WIDESPREAD DENSE FOG. HIGH LEVEL CIRRUS OVER THE EASTERN AND SOUTHERN PORTIONS OF THE CWA HAVE LIMITED FOG DEVELOPMENT A BIT AND RADIATIONAL COOLING. HOWEVER EXPECTING FOG TO BURN OFF QUICKLY THIS MORNING LEADING TO A DRY AND PLEASANT DAY WITH HIGHS IN THE LOW 80S. WINDS WILL BE OFF OF THE LAKE THEREFORE TEMPS WILL BE A FEW DEGREES COOLER ALONG THE LAKE FRONT BUT STILL BE IN THE UPPER 70S TO AROUND 80. REGARDING THE BEACH HAZARDS STATEMENT...THE NORTHEAST WINDS HAVE BEEN SLOW TO INCREASE BUT WILL THIS MORNING TO 10 TO 15 MPH ALONG THE LAKE SHORE AS THE SURFACE HIGH BUILDS SOUTHWARD. THE WAVE MAXIMUM AS DEPICTED BY OUR WAVE MODEL MOVES INTO THE COOK AND LAKE COUNTY INDIANA SHORELINE. WAVE HEIGHTS WILL BE A BIT MORE MARGINAL THAN ORIGINALLY THOUGHT...MAINLY 3 TO 4 FT BUT WAVE OCCASIONALLY TOPPING THAT ARE STILL EXPECTED. HAVE CANCELLED PORTER COUNTY FROM THE HEADLINE THOUGH GIVEN THE TRAJECTORY OF THE WAVE MAXIMUM. SATURDAY THROUGH MONDAY... THE UPPER LEVEL RIDGE EXPANDS OVER THE LOT CWA LATE TONIGHT INTO SATURDAY MORNING BUT REMAINS CENTERED OVER THE OZARKS/SOUTH CENTRAL PLAINS THROUGH THE REST OF THE FORECAST PERIOD. THE SURFACE HIGH PRESSURE CURRENTLY OVER THE GREAT LAKES SHIFTS EAST FRIDAY NIGHT INTO SUNDAY AND THEN SLIDES SOUTH BECOMING CENTERED OVER THE SOUTHEAST ATLANTIC COAST MONDAY NIGHT. MULTIPLE SHORTWAVES WILL ROTATE AROUND THE NORTHERN PORTION OF THE RIDGE WITH THE FIRST ONE SCOOTING NORTH OF THE CWA SATURDAY NIGHT. ADDITIONAL CONVECTION IS EXPECTED ACROSS NORTHERN WI...MI...AND THE NORTHERN HALF OF THE LAKE THROUGH SUNDAY NIGHT. CONVECTION SPREADS DOWN THE LENGTH OF THE LAKE MONDAY AS THE SURFACE HIGH SHIFTS SOUTH AND A BROAD SURFACE LOW OVER THE DAKOTAS SLOWLY SPREADS EAST. HOWEVER NOT ANTICIPATING ANY PRECIP OVER THE LAND PORTION OF THE LOT CWA. UPPER LEVEL TEMPS SLOWLY BUILD WITH 925MB TEMPS REACHING 24-28C ON MONDAY. LOCAL CLIMATOLOGY GUIDANCE SUGGESTS TEMPS SHOULD EASILY REACH THE LOW 90S ON MONDAY. FORECAST SOUNDINGS ALSO INDICATE DEWPOINTS MAY BE A BIT LOWER THAN CURRENTLY FORECAST DUE TO MIXING. THEREFORE KEPT DEWPOINTS A BIT LOWER THAN GUIDANCE WITH MAX HEAT INDICES IN THE UPPER 90S TO AROUND 100. LONG TERM...TUESDAY THROUGH THURSDAY... THE UPPER LEVEL RIDGE REMAINS IN PLACE THROUGH THE EXTENDED BUT A BROAD AREA OF LOW PRESSURE WEAKENS AS IT APPROACHES THE REGION. GUIDANCE IS STILL VERY FUZZY ON WHERE EXACTLY THIS LOW WILL TRACK AND HOW IT WILL IMPACT HIGH TEMPS THROUGH MID WEEK. FOR NOW STILL EXPECTING TEMPS TO CLIMB. 925MB TEMPS REACH 26-30C ALOFT AND EXPECTING THE PEAK OF THE HEAT TO BE TUESDAY AND WEDNESDAY WITH HIGH TEMPS IN THE LOW TO MID 90S. DEWPOINTS WILL BE AROUND 70 RESULTING IN HEAT INDICES AROUND 100-105F. WILL CONTINUE TO MONITOR MODEL TRENDS AS CLOUD COVER AND/OR THE WEAK LOW COULD LIMIT WARMING ON WEDNESDAY...BUT TUESDAY CERTAINLY LOOKS HOT. A WEAK BACKDOOR COLD FRONT MAY MOVE THROUGH THE REGION WEDNESDAY INTO THURSDAY WITH DRIER AND SLIGHTLY COOLER CONDITIONS EXPECTED. TEMPS LOOK LIKE THEY WILL BE IN THE LOW 90S BUT WITH DRIER CONDITIONS...HEAT INDICES IN THE MID TO UPPER 90S ARE EXPECTED. JEE && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 16Z... * NE/ENE WINDS AROUND 10 KT MAY INCREASE TO 12-14KT BY EARLY THIS AFTERNOON. BEACHLER //DISCUSSION...UPDATED 12Z... HIGH PRESSURE CONTINUES TO BUILD SOUTHEAST FROM THE UPPER MISSISSIPPI VALLEY. DRIER AIR OOZING IN FROM THIS HAS HELPED TO ABATE THE FOG ACROSS MOST OF THE TAF SITES EARLY THIS MORNING. SOME STRATUS ACROSS GYY AND JUST SOUTH OF MDW SHOULD QUICKLY TURN INTO A CU FIELD THIS MORNING. THE HIGH WILL TRANSLATE SLOWLY EAST THROUGH THE TAF PERIOD. WINDS WILL PICK UP DURING THE MID TO LATE MORNING WITH THE VAD WIND PROFILE INDICATING 10-15KT WITHIN 2000 FT OF THE SURFACE. THE WINDS WILL BE OFF THE LAKE AS WELL...AND CLIMATOLOGY POINTS TO THE DIRECTION BEING CLOSER TO ENE OR EVEN E BY AFTERNOON. SPEEDS SHOULD DIMINISH QUICKLY COME THIS EVE. FOG WILL BE LESS OF A THREAT TONIGHT DUE TO DRYING IN THE LOW- LEVELS...BUT STILL SOME PATCHY FOG MAY BE SEEN ESPECIALLY IN THOSE AREAS THAT SAW MORE OF AN APPRECIABLE RAIN DURING THURSDAY /LIKE RFD/. MTF //ORD AND MDW CONFIDENCE...UPDATED 16Z... * MEDIUM CONFIDENCE THAT BROKEN STRATUS WILL STAY JUST SOUTH OF MDW. * MEDIUM CONFIDENCE IN WIND SPEEDS STAY AOB 10KT TODAY. BEACHLER //OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z... SATURDAY NIGHT-MONDAY...VFR. TUESDAY-WEDNESDAY...VFR AND HOT DURING THE DAYS. SLIGHT CHC OF STORMS WED NIGHT. THURSDAY...VFR. MTF && .MARINE... 306 AM CDT HIGH PRESSURE WILL EXPAND ITS WAY DOWN THE LAKE TODAY LEADING TO NORTHEAST WINDS ACROSS NEARSHORE AREAS WHILE DIMINISHING WINDS OVER THE OPEN WATER. AS THE HIGH DEPARTS OFF TO THE EAST IT WILL STALL WITH BROAD LOW PRESSURE DEVELOPING OVER THE NORTHERN PLAINS. THIS PATTERN WILL PERSIST INTO NEXT WEEK MEANING PROLONGED SOUTHERLY FLOW OVER THE LAKE. SOME 30 KT GUSTS IN THE NORTH ON SUNDAY COULD BE SEEN. THIS OVERALL WEATHER PATTERN CAN AT TIMES LEAD TO A STRONG COMPLEX OR TWO OF STORMS FOR THE NORTHERN PART OF THE LAKE...AND THAT WOULD SEEM MOST FAVORED SOMETIME IN THE MON NIGHT-WED NIGHT TIME FRAME...THOUGH CONFIDENCE ON THIS REMAINS LOW. EVENTUALLY THE BROAD LOW WILL SHIFT OVER THE LAKE DURING THE MIDWEEK PERIOD. MTF && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion National Weather Service Lincoln IL 950 AM CDT Fri Aug 23 2013 .DISCUSSION... ISSUED 949 AM CDT Fri Aug 23 2013 Areas of dense fog north of I-74 has been lifting into a stratus deck this morning, and should continue to thin from the edges over the next couple hours as diurnal mixing increases. Otherwise, high pressure north of Lake Superior will bring a 5-10 mph northeast wind flow to the region causing dewpoints will gradually fall into the low/mid 60s from north to south by late afternoon. Subsidence on the south side of the ridge should provide mostly sunny skies and seasonable highs in the mid 80s. 25 && .AVIATION... ISSUED 657 AM CDT Fri Aug 23 2013 Generally quiet/VFR aviation weather conditions expected across the central Illinois terminals through the 12Z TAF valid time. Patchy fog/stratus may briefly cause MVFR/IFR conditions for a couple hours this morning, but otherwise cloud cover should be minimal. While light fog can not be ruled out overnight tonight, the drier air filtering into the area around the south side of a an area high pressure should keep the risk to a minimum. Bak && .PREV DISCUSSION... ISSUED 240 AM CDT Fri Aug 23 2013 SHORT TERM...Today through Saturday... Initial frontal passage has taken place over all of central and southeast Illinois early this morning, but drier air lingers a bit further back as lower 60s dew points now starting to enter the far northern CWA. A cluster of thunderstorms developed from Springfield to Decatur along the remnants of an old boundary from earlier, in an area with MUCAPE`s of around 1000 J/kg, and the cluster has been increasing a bit over the last hour or so as it moves south-southeast. Latest model guidance suggesting scattered showers/storms through about mid morning over about the southeast third of the forecast area. Further north, fog has been thickening and increasing over the northeast third of the state, where skies have cleared and the drier air has arrived. So far visibilities in our area have been staying up as a band of altocumulus has persisted, but clearing has been taking place from Galesburg to Lacon. However, the lower visibilities have been in areas that had quite a bit of rain on Thursday, and much of our forecast area had a quarter inch or less except in isolated spots. So, the question is how much of the forecast area, if any, will see dense fog this morning. HRRR guidance is the most pessimistic with it fairly widespread along and north of I-74, while the most recent RAP has scaled back and went mainly patchy dense fog in the same area. Currently have mention of 1/2 mile visibility in fog in this area through about 9 am, but will have to monitor for any significant advection from the northeast. Once the fog and rain moves out, quiet weather expected through the first part of the weekend. High pressure drifting through the Great Lakes will advect some drier air in from the east, but should still see highs in the mid-upper 80s. LONG TERM...Sunday through Thursday... Main weather story over the coming week continues to be with the expanding heat over the center of the nation, as a large dome of high pressure aloft drifts eastward. Any MCS ridge riders will be well to our north, and will continue the dry forecast for next week. Highs to rise through the 90s much of the week as thermal ridge builds eastward. Core of this ridge will be in the area on Wednesday. Latest ECMWF showing upper 90s over most of the forecast area that day. Have continued to trend temperatures up a degree or two from blended guidance with mid 90s widespread on Wednesday. Heat index values of just over 100 likely across the western CWA Monday-Tuesday and everywhere Wednesday. On Thursday, the thermal ridge starts shifting westward again, but should still see highs in the 93-95 range. Geelhart && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
913 AM CDT FRI AUG 23 2013 .DISCUSSION... 352 AM CDT SYNOPSIS...A LARGE RIDGE OVER THE CENTRAL US SPREADS EAST OVER THE GREAT LAKES. A WARMING TREND IS IN STORE THROUGH MID NEXT WEEK WITH HIGHS IN THE 90S AND HEAT INDICES IN THE 100S POSSIBLE. TODAY... HIGH PRESSURE IS OVER THE GREAT LAKES WITH A LARGE RIDGE ALOFT CENTERED OVER THE SOUTH CENTRAL GREAT PLAINS. PRIMARILY CLEAR SKIES OVERNIGHT COMBINED WITH WEAK TO CALM WINDS AND WET GROUND RESULTED IN AREAS TO WIDESPREAD DENSE FOG. HIGH LEVEL CIRRUS OVER THE EASTERN AND SOUTHERN PORTIONS OF THE CWA HAVE LIMITED FOG DEVELOPMENT A BIT AND RADIATIONAL COOLING. HOWEVER EXPECTING FOG TO BURN OFF QUICKLY THIS MORNING LEADING TO A DRY AND PLEASANT DAY WITH HIGHS IN THE LOW 80S. WINDS WILL BE OFF OF THE LAKE THEREFORE TEMPS WILL BE A FEW DEGREES COOLER ALONG THE LAKE FRONT BUT STILL BE IN THE UPPER 70S TO AROUND 80. REGARDING THE BEACH HAZARDS STATEMENT...THE NORTHEAST WINDS HAVE BEEN SLOW TO INCREASE BUT WILL THIS MORNING TO 10 TO 15 MPH ALONG THE LAKE SHORE AS THE SURFACE HIGH BUILDS SOUTHWARD. THE WAVE MAXIMUM AS DEPICTED BY OUR WAVE MODEL MOVES INTO THE COOK AND LAKE COUNTY INDIANA SHORELINE. WAVE HEIGHTS WILL BE A BIT MORE MARGINAL THAN ORIGINALLY THOUGHT...MAINLY 3 TO 4 FT BUT WAVE OCCASIONALLY TOPPING THAT ARE STILL EXPECTED. HAVE CANCELLED PORTER COUNTY FROM THE HEADLINE THOUGH GIVEN THE TRAJECTORY OF THE WAVE MAXIMUM. SATURDAY THROUGH MONDAY... THE UPPER LEVEL RIDGE EXPANDS OVER THE LOT CWA LATE TONIGHT INTO SATURDAY MORNING BUT REMAINS CENTERED OVER THE OZARKS/SOUTH CENTRAL PLAINS THROUGH THE REST OF THE FORECAST PERIOD. THE SURFACE HIGH PRESSURE CURRENTLY OVER THE GREAT LAKES SHIFTS EAST FRIDAY NIGHT INTO SUNDAY AND THEN SLIDES SOUTH BECOMING CENTERED OVER THE SOUTHEAST ATLANTIC COAST MONDAY NIGHT. MULTIPLE SHORTWAVES WILL ROTATE AROUND THE NORTHERN PORTION OF THE RIDGE WITH THE FIRST ONE SCOOTING NORTH OF THE CWA SATURDAY NIGHT. ADDITIONAL CONVECTION IS EXPECTED ACROSS NORTHERN WI...MI...AND THE NORTHERN HALF OF THE LAKE THROUGH SUNDAY NIGHT. CONVECTION SPREADS DOWN THE LENGTH OF THE LAKE MONDAY AS THE SURFACE HIGH SHIFTS SOUTH AND A BROAD SURFACE LOW OVER THE DAKOTAS SLOWLY SPREADS EAST. HOWEVER NOT ANTICIPATING ANY PRECIP OVER THE LAND PORTION OF THE LOT CWA. UPPER LEVEL TEMPS SLOWLY BUILD WITH 925MB TEMPS REACHING 24-28C ON MONDAY. LOCAL CLIMATOLOGY GUIDANCE SUGGESTS TEMPS SHOULD EASILY REACH THE LOW 90S ON MONDAY. FORECAST SOUNDINGS ALSO INDICATE DEWPOINTS MAY BE A BIT LOWER THAN CURRENTLY FORECAST DUE TO MIXING. THEREFORE KEPT DEWPOINTS A BIT LOWER THAN GUIDANCE WITH MAX HEAT INDICES IN THE UPPER 90S TO AROUND 100. LONG TERM...TUESDAY THROUGH THURSDAY... THE UPPER LEVEL RIDGE REMAINS IN PLACE THROUGH THE EXTENDED BUT A BROAD AREA OF LOW PRESSURE WEAKENS AS IT APPROACHES THE REGION. GUIDANCE IS STILL VERY FUZZY ON WHERE EXACTLY THIS LOW WILL TRACK AND HOW IT WILL IMPACT HIGH TEMPS THROUGH MID WEEK. FOR NOW STILL EXPECTING TEMPS TO CLIMB. 925MB TEMPS REACH 26-30C ALOFT AND EXPECTING THE PEAK OF THE HEAT TO BE TUESDAY AND WEDNESDAY WITH HIGH TEMPS IN THE LOW TO MID 90S. DEWPOINTS WILL BE AROUND 70 RESULTING IN HEAT INDICES AROUND 100-105F. WILL CONTINUE TO MONITOR MODEL TRENDS AS CLOUD COVER AND/OR THE WEAK LOW COULD LIMIT WARMING ON WEDNESDAY...BUT TUESDAY CERTAINLY LOOKS HOT. A WEAK BACKDOOR COLD FRONT MAY MOVE THROUGH THE REGION WEDNESDAY INTO THURSDAY WITH DRIER AND SLIGHTLY COOLER CONDITIONS EXPECTED. TEMPS LOOK LIKE THEY WILL BE IN THE LOW 90S BUT WITH DRIER CONDITIONS...HEAT INDICES IN THE MID TO UPPER 90S ARE EXPECTED. JEE && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 14Z... * NE/ENE WINDS AROUND 10 KT LATE THIS MORNING THEN SPEEDS MAY INCREASE TO 12-14KT BY EARLY THIS AFTERNOON. BEACHLER //DISCUSSION...UPDATED 12Z... HIGH PRESSURE CONTINUES TO BUILD SOUTHEAST FROM THE UPPER MISSISSIPPI VALLEY. DRIER AIR OOZING IN FROM THIS HAS HELPED TO ABATE THE FOG ACROSS MOST OF THE TAF SITES EARLY THIS MORNING. SOME STRATUS ACROSS GYY AND JUST SOUTH OF MDW SHOULD QUICKLY TURN INTO A CU FIELD THIS MORNING. THE HIGH WILL TRANSLATE SLOWLY EAST THROUGH THE TAF PERIOD. WINDS WILL PICK UP DURING THE MID TO LATE MORNING WITH THE VAD WIND PROFILE INDICATING 10-15KT WITHIN 2000 FT OF THE SURFACE. THE WINDS WILL BE OFF THE LAKE AS WELL...AND CLIMATOLOGY POINTS TO THE DIRECTION BEING CLOSER TO ENE OR EVEN E BY AFTERNOON. SPEEDS SHOULD DIMINISH QUICKLY COME THIS EVE. FOG WILL BE LESS OF A THREAT TONIGHT DUE TO DRYING IN THE LOW- LEVELS...BUT STILL SOME PATCHY FOG MAY BE SEEN ESPECIALLY IN THOSE AREAS THAT SAW MORE OF AN APPRECIABLE RAIN DURING THURSDAY /LIKE RFD/. MTF //ORD AND MDW CONFIDENCE...UPDATED 14Z... * MEDIUM CONFIDENCE THAT BROKEN STRATUS WILL STAY JUST SOUTH OF MDW. * MEDIUM CONFIDENCE IN WIND SPEEDS STAY AOB 10KT TODAY. BEACHLER //OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z... SATURDAY NIGHT-MONDAY...VFR. TUESDAY-WEDNESDAY...VFR AND HOT DURING THE DAYS. SLIGHT CHC OF STORMS WED NIGHT. THURSDAY...VFR. MTF && .MARINE... 306 AM CDT HIGH PRESSURE WILL EXPAND ITS WAY DOWN THE LAKE TODAY LEADING TO NORTHEAST WINDS ACROSS NEARSHORE AREAS WHILE DIMINISHING WINDS OVER THE OPEN WATER. AS THE HIGH DEPARTS OFF TO THE EAST IT WILL STALL WITH BROAD LOW PRESSURE DEVELOPING OVER THE NORTHERN PLAINS. THIS PATTERN WILL PERSIST INTO NEXT WEEK MEANING PROLONGED SOUTHERLY FLOW OVER THE LAKE. SOME 30 KT GUSTS IN THE NORTH ON SUNDAY COULD BE SEEN. THIS OVERALL WEATHER PATTERN CAN AT TIMES LEAD TO A STRONG COMPLEX OR TWO OF STORMS FOR THE NORTHERN PART OF THE LAKE...AND THAT WOULD SEEM MOST FAVORED SOMETIME IN THE MON NIGHT-WED NIGHT TIME FRAME...THOUGH CONFIDENCE ON THIS REMAINS LOW. EVENTUALLY THE BROAD LOW WILL SHIFT OVER THE LAKE DURING THE MIDWEEK PERIOD. MTF && .LOT WATCHES/WARNINGS/ADVISORIES... IL...BEACH HAZARDS STATEMENT...ILZ014 UNTIL 7 PM FRIDAY. IN...BEACH HAZARDS STATEMENT...INZ001 UNTIL 7 PM FRIDAY. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion National Weather Service Lincoln IL 657 AM CDT Fri Aug 23 2013 .DISCUSSION... ISSUED 240 AM CDT Fri Aug 23 2013 SHORT TERM...Today through Saturday... Initial frontal passage has taken place over all of central and southeast Illinois early this morning, but drier air lingers a bit further back as lower 60s dew points now starting to enter the far northern CWA. A cluster of thunderstorms developed from Springfield to Decatur along the remnants of an old boundary from earlier, in an area with MUCAPE`s of around 1000 J/kg, and the cluster has been increasing a bit over the last hour or so as it moves south-southeast. Latest model guidance suggesting scattered showers/storms through about mid morning over about the southeast third of the forecast area. Further north, fog has been thickening and increasing over the northeast third of the state, where skies have cleared and the drier air has arrived. So far visibilities in our area have been staying up as a band of altocumulus has persisted, but clearing has been taking place from Galesburg to Lacon. However, the lower visibilities have been in areas that had quite a bit of rain on Thursday, and much of our forecast area had a quarter inch or less except in isolated spots. So, the question is how much of the forecast area, if any, will see dense fog this morning. HRRR guidance is the most pessimistic with it fairly widespread along and north of I-74, while the most recent RAP has scaled back and went mainly patchy dense fog in the same area. Currently have mention of 1/2 mile visibility in fog in this area through about 9 am, but will have to monitor for any significant advection from the northeast. Once the fog and rain moves out, quiet weather expected through the first part of the weekend. High pressure drifting through the Great Lakes will advect some drier air in from the east, but should still see highs in the mid-upper 80s. LONG TERM...Sunday through Thursday... Main weather story over the coming week continues to be with the expanding heat over the center of the nation, as a large dome of high pressure aloft drifts eastward. Any MCS ridge riders will be well to our north, and will continue the dry forecast for next week. Highs to rise through the 90s much of the week as thermal ridge builds eastward. Core of this ridge will be in the area on Wednesday. Latest ECMWF showing upper 90s over most of the forecast area that day. Have continued to trend temperatures up a degree or two from blended guidance with mid 90s widespread on Wednesday. Heat index values of just over 100 likely across the western CWA Monday-Tuesday and everywhere Wednesday. On Thursday, the thermal ridge starts shifting westward again, but should still see highs in the 93-95 range. Geelhart && .AVIATION... ISSUED 657 AM CDT Fri Aug 23 2013 Generally quiet/VFR aviation weather conditions expected across the central Illinois terminals through the 12Z TAF valid time. Patchy fog/stratus may briefly cause MVFR/IFR conditions for a couple hours this morning, but otherwise cloud cover should be minimal. While light fog can not be ruled out overnight tonight, the drier air filtering into the area around the south side of a an area high pressure should keep the risk to a minimum. Bak && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
314 AM CDT FRI AUG 23 2013 .DISCUSSION... 829 PM CDT A FEW LIGHT SHOWERS CONTINUE TO MOVE SOUTHWARD OUT OF THE EXTREME SOUTHERN CWA THIS EVENING. SATELLITE IMAGERY AND A LOOK OUT THE WINDOW SHOWS CLOUDS CLEARING FROM THE NORTHWEST. WINDS HAVE DIMINISHED ACROSS THE AREA WITH DEWPOINTS REMAINING IN THE MID AND UPPER 60S. HAVE MADE A FEW ADJUSTMENTS TO THE FORECAST MAINLY TO ADD FOG MENTION TO MOST AREAS. DRIER AIR WILL SLOWLY FILTER SOUTHWARD INTO THE AREA TONIGHT BUT THE LIGHT WINDS AND CLEARING SKIES WILL ALLOW FOR GOOD RADIATIONAL COOLING SO EXPECT SMALL T/TD SPREADS WITH WET TO EVEN SATURATED GROUND PROMOTING FOG DEVELOPMENT. SOME OF THIS MAY BE DENSE SO WILL NEED TO MONITOR TRENDS EARLY TONIGHT FOR A POSSIBLE ADVISORY IF COVERAGE BECOMES GREAT ENOUGH. THE MAIN AREA OF CONCERN WILL BE INLAND OF THE LAKE AND ACROSS THE OUTER CHICAGO SUBURBS TO POINTS SOUTH AND WEST. FOG MAY LINGER PAST DAYBREAK WITH WINDS SLOWLY COMING UP AMID THE PRESENCE OF HIGH PRESSURE. MDB //PREV DISCUSSION... 329 PM CDT TONIGHT THROUGH FRIDAY NIGHT...CANADIAN HIGH PRESSURE WILL SETTLE INTO THE GREAT LAKES REGION BEHIND A COLD FRONT. THAT FRONT IS STILL NOT QUITE THROUGH NORTHERN IL YET. IT IS RIGHT ALONG THE WI/IL BORDER AT 330 THIS AFTERNOON AND WILL SLOWLY DROP SOUTHWARD THROUGH THE LOT FORECAST AREA. UNTIL THAT FRONT GETS COMPLETELY OUT OF THE AREA...THERE WILL BE JUST ENOUGH INSTABILITY AND LOW LEVEL CONVERGENCE TO KEEP THE MENTION OF A CHANCE FOR SHOWERS IN THE NORTH AND SHOWERS AND THUNDERSTORMS ROUGHLY SOUTH OF CHICAGO. THE BETTER CHANCE FOR SHOWERS AND THUNDERSTORMS FROM LATE THIS AFTERNOON THROUGH LATE EVENING WILL BE IN FAR SOUTHERN LOT FORECAST AREA WHERE SHORTWAVE ENERGY WILL STILL BE IN THE VICINITY. DRIER AIR WILL FINALLY SPILL INTO NORTHERN IL AFTER MIDNIGHT AND HANG AROUND THROUGH FRIDAY AND FRIDAY NIGHT WITH DRY WEATHER. EXPECTING MUCH MORE SUNSHINE FRIDAY THAN TODAY...SO MAX TEMPS WILL BE IN THE LOWER 80S...EXCEPT A FEW DEGREES COOLER NEAR THE LAKE WITH NORTHEAST WINDS. MRC SATURDAY AND SUNDAY...SURFACE HIGH PRESSURE SLIDES OVER THE EASTERN US DURING THIS PERIOD WHILE A 591 TO 594 DM 500 MB HIGH PRESSURE BUILDS ACROSS THE CENTRAL US. SOME MODELS SHOW A SHORTWAVE MOVING THROUGH SATURDAY AFTERNOON AND EVENING...BRINGING A SHOT AT PRECIP. HOWEVER...THE MODELS ARE GENERALLY KEEPING THE PRECIP TO THE WEST AND NORTHWEST. WILL KEEP THE PRECIP OUT OF THE FORECAST...AS THE BEST WARM AIR ADVECTION AND COINCIDING Q VECTOR CONVERGENCE DOES LOOK TO BE TO THE WEST AND NORTHWEST. THE DRY FORECAST CONTINUES FOR SUNDAY...WITH THE PRECIPITATION STAYING TO THE NORTH...OVER NORTHERN WISCONSIN...THE UPPER PENINSULA AND NORTHERN LAKE MICHIGAN. TEMPS ON SATURDAY WARM A BIT TO THE LOWER TO MID 80S. THEN AT 00Z ON MONDAY 925 TEMPS REACH ABOUT 23 TO 25 C...BRINGING TEMPS IN THE UPPER 80S TO AROUND 90 ON SUNDAY. MONDAY THROUGH THURSDAY...A QUIET AND TOASTY FORECAST IS IN STORE FOR NEXT WEEK. THE LOWER TO MID 90S LOOK TO STICK AROUND THROUGH AT LEAST THURSDAY AS THE 500 MB HIGH LINGERS OVER THE CENTRAL US AND 925 MB TEMPS STAY IN THE UPPER 20S TO AROUND 30 C. HOWEVER...SOME MODELS CONTINUE TO HINT AT A BACKDOOR COLD FRONT SLIDING THROUGH WEDNESDAY. THE ECMWF IS CONTINUALLY TRENDING AWAY FROM THIS THOUGH...SO STICKING WITH THE WARM FORECAST. TWO PASSING SURFACE LOW PRESSURES COUPLED WITH A FEW WEAK WAVES RIDING ALONG THE NORTHERN EDGE OF THE 500 MB HIGH WILL BRING PRECIP CHANCES TO THE NORTH OF ILLINOIS DURING THIS TIME. MEB && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * FOG...MAINLY SHALLOW...THROUGH 13Z. * ENE WINDS AROUND 10 KT LATE THIS MORNING AND AFTERNOON. //DISCUSSION...UPDATED 06Z... HIGH PRESSURE IS OOZING ITS WAY SOUTHWARD ACROSS THE UPPER MIDWEST EARLY THIS MORNING. THE LACK OF A STRONG GRADIENT ON ITS LEADING EDGE AND THE WET GROUND CONDITIONS LOCALLY HAVE ALLOWED FOR FOG DEVELOPMENT. THIS WILL CONTINUE THROUGH DAYBREAK AND LIKELY AN HOUR OR SO AFTER. THE FOG IS LIKELY TO BE SHALLOW AT FIRST BUT MAY SETTLE IN TOWARD DAYBREAK AS THICKER. A SLIGHT NORTHEAST WIND COMPONENT OFF THE LAKE SHOULD HELP THE PREVAILING VISIBILITY AT ORD AND MDW REMAIN UP. WINDS WILL PICK UP DURING THE MID TO LATE MORNING...WITH THE NORTHEAST COMPONENT OFF THE LAKE APPROACHING 10 KT. CLIMATOLOGY POINTS TO THIS BEING CLOSER TO ENE OR EVEN E BY AFTERNOON. SPEEDS SHOULD DIMINISH QUICKLY IN THE EVE. FOG WILL BE LESS OF A THREAT FRI NIGHT DUE TO DRYING IN THE LOW-LEVELS...BUT STILL SOME PATCHY FOG MAY BE SEEN ESPECIALLY IN THOSE AREAS THAT SAW MORE APPRECIABLE RAIN DURING THURSDAY. //ORD AND MDW CONFIDENCE...UPDATED 06Z... * MEDIUM CONFIDENCE ON PREVAILING VISIBILITIES REMAINING 5SM OR GREATER THIS MORNING. * MEDIUM CONFIDENCE ON WIND SPEEDS ATTAINING 10KT OR HIGHER. //OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 00Z... SAT THROUGH WED...VFR. WX NIL. MTF && .MARINE... 306 AM CDT HIGH PRESSURE WILL EXPAND ITS WAY DOWN THE LAKE TODAY LEADING TO NORTHEAST WINDS ACROSS NEARSHORE AREAS WHILE DIMINISHING WINDS OVER THE OPEN WATER. AS THE HIGH DEPARTS OFF TO THE EAST IT WILL STALL WITH BROAD LOW PRESSURE DEVELOPING OVER THE NORTHERN PLAINS. THIS PATTERN WILL PERSIST INTO NEXT WEEK MEANING PROLONGED SOUTHERLY FLOW OVER THE LAKE. SOME 30 KT GUSTS IN THE NORTH ON SUNDAY COULD BE SEEN. THIS OVERALL WEATHER PATTERN CAN AT TIMES LEAD TO A STRONG COMPLEX OR TWO OF STORMS FOR THE NORTHERN PART OF THE LAKE...AND THAT WOULD SEEM MOST FAVORED SOMETIME IN THE MON NIGHT-WED NIGHT TIME FRAME...THOUGH CONFIDENCE ON THIS REMAINS LOW. EVENTUALLY THE BROAD LOW WILL SHIFT OVER THE LAKE DURING THE MIDWEEK PERIOD. MTF && .LOT WATCHES/WARNINGS/ADVISORIES... IL...DENSE FOG ADVISORY...ILZ003-ILZ004-ILZ008-ILZ010-ILZ011-ILZ019- ILZ020-ILZ021-ILZ022-ILZ023-ILZ032-ILZ033-ILZ039 UNTIL 9 AM FRIDAY. BEACH HAZARDS STATEMENT...ILZ014 UNTIL 9 AM FRIDAY. IN...BEACH HAZARDS STATEMENT...INZ001-INZ002 UNTIL 9 AM FRIDAY. DENSE FOG ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 9 AM FRIDAY. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion National Weather Service Lincoln IL 243 AM CDT Fri Aug 23 2013 .DISCUSSION... ISSUED 240 AM CDT Fri Aug 23 2013 SHORT TERM...Today through Saturday... Initial frontal passage has taken place over all of central and southeast Illinois early this morning, but drier air lingers a bit further back as lower 60s dew points now starting to enter the far northern CWA. A cluster of thunderstorms developed from Springfield to Decatur along the remnants of an old boundary from earlier, in an area with MUCAPE`s of around 1000 J/kg, and the cluster has been increasing a bit over the last hour or so as it moves south-southeast. Latest model guidance suggesting scattered showers/storms through about mid morning over about the southeast third of the forecast area. Further north, fog has been thickening and increasing over the northeast third of the state, where skies have cleared and the drier air has arrived. So far visibilities in our area have been staying up as a band of altocumulus has persisted, but clearing has been taking place from Galesburg to Lacon. However, the lower visibilities have been in areas that had quite a bit of rain on Thursday, and much of our forecast area had a quarter inch or less except in isolated spots. So, the question is how much of the forecast area, if any, will see dense fog this morning. HRRR guidance is the most pessimistic with it fairly widespread along and north of I-74, while the most recent RAP has scaled back and went mainly patchy dense fog in the same area. Currently have mention of 1/2 mile visibility in fog in this area through about 9 am, but will have to monitor for any significant advection from the northeast. Once the fog and rain moves out, quiet weather expected through the first part of the weekend. High pressure drifting through the Great Lakes will advect some drier air in from the east, but should still see highs in the mid-upper 80s. LONG TERM...Sunday through Thursday... Main weather story over the coming week continues to be with the expanding heat over the center of the nation, as a large dome of high pressure aloft drifts eastward. Any MCS ridge riders will be well to our north, and will continue the dry forecast for next week. Highs to rise through the 90s much of the week as thermal ridge builds eastward. Core of this ridge will be in the area on Wednesday. Latest ECMWF showing upper 90s over most of the forecast area that day. Have continued to trend temperatures up a degree or two from blended guidance with mid 90s widespread on Wednesday. Heat index values of just over 100 likely across the western CWA Monday-Tuesday and everywhere Wednesday. On Thursday, the thermal ridge starts shifting westward again, but should still see highs in the 93-95 range. Geelhart && .AVIATION... ISSUED 1149 PM CDT Thu Aug 22 2013 A couple of convective updrafts developed along the cold front just southeast of DEC in the last hour. MLCAPE values of 1000-1500 J/kg will keep enough elevated instability in place for a few lightning strikes from the stronger updrafts. Still, coverage will be isolated and we only included a VCTS for DEC and SPI where the front will linger the next few hours. MVFR/IFR fog is expected to develop farther north where skies may clear out under light winds. BMI/CMI were closer to the rainfall from early today, so fog formation may become thicker in those areas. We included tempos for 1SM BR 10-13z, but localized 1/4SM FG will be possible toward sunrise. PIA fog may dip to IFR, but the HRRR shows 1/4SM FG for all 3 northern TAF sites between 08z and 14z. We did not hit fog that hard yet, but will monitor trends closely. Shimon && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1253 AM CDT FRI AUG 23 2013 .DISCUSSION... 829 PM CDT A FEW LIGHT SHOWERS CONTINUE TO MOVE SOUTHWARD OUT OF THE EXTREME SOUTHERN CWA THIS EVENING. SATELLITE IMAGERY AND A LOOK OUT THE WINDOW SHOWS CLOUDS CLEARING FROM THE NORTHWEST. WINDS HAVE DIMINISHED ACROSS THE AREA WITH DEWPOINTS REMAINING IN THE MID AND UPPER 60S. HAVE MADE A FEW ADJUSTMENTS TO THE FORECAST MAINLY TO ADD FOG MENTION TO MOST AREAS. DRIER AIR WILL SLOWLY FILTER SOUTHWARD INTO THE AREA TONIGHT BUT THE LIGHT WINDS AND CLEARING SKIES WILL ALLOW FOR GOOD RADIATIONAL COOLING SO EXPECT SMALL T/TD SPREADS WITH WET TO EVEN SATURATED GROUND PROMOTING FOG DEVELOPMENT. SOME OF THIS MAY BE DENSE SO WILL NEED TO MONITOR TRENDS EARLY TONIGHT FOR A POSSIBLE ADVISORY IF COVERAGE BECOMES GREAT ENOUGH. THE MAIN AREA OF CONCERN WILL BE INLAND OF THE LAKE AND ACROSS THE OUTER CHICAGO SUBURBS TO POINTS SOUTH AND WEST. FOG MAY LINGER PAST DAYBREAK WITH WINDS SLOWLY COMING UP AMID THE PRESENCE OF HIGH PRESSURE. MDB //PREV DISCUSSION... 329 PM CDT TONIGHT THROUGH FRIDAY NIGHT...CANADIAN HIGH PRESSURE WILL SETTLE INTO THE GREAT LAKES REGION BEHIND A COLD FRONT. THAT FRONT IS STILL NOT QUITE THROUGH NORTHERN IL YET. IT IS RIGHT ALONG THE WI/IL BORDER AT 330 THIS AFTERNOON AND WILL SLOWLY DROP SOUTHWARD THROUGH THE LOT FORECAST AREA. UNTIL THAT FRONT GETS COMPLETELY OUT OF THE AREA...THERE WILL BE JUST ENOUGH INSTABILITY AND LOW LEVEL CONVERGENCE TO KEEP THE MENTION OF A CHANCE FOR SHOWERS IN THE NORTH AND SHOWERS AND THUNDERSTORMS ROUGHLY SOUTH OF CHICAGO. THE BETTER CHANCE FOR SHOWERS AND THUNDERSTORMS FROM LATE THIS AFTERNOON THROUGH LATE EVENING WILL BE IN FAR SOUTHERN LOT FORECAST AREA WHERE SHORTWAVE ENERGY WILL STILL BE IN THE VICINITY. DRIER AIR WILL FINALLY SPILL INTO NORTHERN IL AFTER MIDNIGHT AND HANG AROUND THROUGH FRIDAY AND FRIDAY NIGHT WITH DRY WEATHER. EXPECTING MUCH MORE SUNSHINE FRIDAY THAN TODAY...SO MAX TEMPS WILL BE IN THE LOWER 80S...EXCEPT A FEW DEGREES COOLER NEAR THE LAKE WITH NORTHEAST WINDS. MRC SATURDAY AND SUNDAY...SURFACE HIGH PRESSURE SLIDES OVER THE EASTERN US DURING THIS PERIOD WHILE A 591 TO 594 DM 500 MB HIGH PRESSURE BUILDS ACROSS THE CENTRAL US. SOME MODELS SHOW A SHORTWAVE MOVING THROUGH SATURDAY AFTERNOON AND EVENING...BRINGING A SHOT AT PRECIP. HOWEVER...THE MODELS ARE GENERALLY KEEPING THE PRECIP TO THE WEST AND NORTHWEST. WILL KEEP THE PRECIP OUT OF THE FORECAST...AS THE BEST WARM AIR ADVECTION AND COINCIDING Q VECTOR CONVERGENCE DOES LOOK TO BE TO THE WEST AND NORTHWEST. THE DRY FORECAST CONTINUES FOR SUNDAY...WITH THE PRECIPITATION STAYING TO THE NORTH...OVER NORTHERN WISCONSIN...THE UPPER PENINSULA AND NORTHERN LAKE MICHIGAN. TEMPS ON SATURDAY WARM A BIT TO THE LOWER TO MID 80S. THEN AT 00Z ON MONDAY 925 TEMPS REACH ABOUT 23 TO 25 C...BRINGING TEMPS IN THE UPPER 80S TO AROUND 90 ON SUNDAY. MONDAY THROUGH THURSDAY...A QUIET AND TOASTY FORECAST IS IN STORE FOR NEXT WEEK. THE LOWER TO MID 90S LOOK TO STICK AROUND THROUGH AT LEAST THURSDAY AS THE 500 MB HIGH LINGERS OVER THE CENTRAL US AND 925 MB TEMPS STAY IN THE UPPER 20S TO AROUND 30 C. HOWEVER...SOME MODELS CONTINUE TO HINT AT A BACKDOOR COLD FRONT SLIDING THROUGH WEDNESDAY. THE ECMWF IS CONTINUALLY TRENDING AWAY FROM THIS THOUGH...SO STICKING WITH THE WARM FORECAST. TWO PASSING SURFACE LOW PRESSURES COUPLED WITH A FEW WEAK WAVES RIDING ALONG THE NORTHERN EDGE OF THE 500 MB HIGH WILL BRING PRECIP CHANCES TO THE NORTH OF ILLINOIS DURING THIS TIME. MEB && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * FOG...MAINLY SHALLOW...THROUGH 13Z. * ENE WINDS AROUND 10 KT LATE THIS MORNING AND AFTERNOON. //DISCUSSION...UPDATED 06Z... HIGH PRESSURE IS OOZING ITS WAY SOUTHWARD ACROSS THE UPPER MIDWEST EARLY THIS MORNING. THE LACK OF A STRONG GRADIENT ON ITS LEADING EDGE AND THE WET GROUND CONDITIONS LOCALLY HAVE ALLOWED FOR FOG DEVELOPMENT. THIS WILL CONTINUE THROUGH DAYBREAK AND LIKELY AN HOUR OR SO AFTER. THE FOG IS LIKELY TO BE SHALLOW AT FIRST BUT MAY SETTLE IN TOWARD DAYBREAK AS THICKER. A SLIGHT NORTHEAST WIND COMPONENT OFF THE LAKE SHOULD HELP THE PREVAILING VISIBILITY AT ORD AND MDW REMAIN UP. WINDS WILL PICK UP DURING THE MID TO LATE MORNING...WITH THE NORTHEAST COMPONENT OFF THE LAKE APPROACHING 10 KT. CLIMATOLOGY POINTS TO THIS BEING CLOSER TO ENE OR EVEN E BY AFTERNOON. SPEEDS SHOULD DIMINISH QUICKLY IN THE EVE. FOG WILL BE LESS OF A THREAT FRI NIGHT DUE TO DRYING IN THE LOW-LEVELS...BUT STILL SOME PATCHY FOG MAY BE SEEN ESPECIALLY IN THOSE AREAS THAT SAW MORE APPRECIABLE RAIN DURING THURSDAY. //ORD AND MDW CONFIDENCE...UPDATED 06Z... * MEDIUM CONFIDENCE ON PREVAILING VISIBILITIES REMAINING 5SM OR GREATER THIS MORNING. * MEDIUM CONFIDENCE ON WIND SPEEDS ATTAINING 10KT OR HIGHER. //OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 00Z... SAT THROUGH WED...VFR. WX NIL. MTF && .MARINE... 329 PM CDT HIGH PRESSURE OF 30.1 INCHES BUILDING ACROSS THE UPPER MIDWEST WILL SHIFT EAST OVER LAKE MICHIGAN ON FRIDAY...THEN OVER THE EASTERN LAKES SATURDAY. A BROAD AREA OF LOW PRESSURE AVERAGING 29.7 INCHES WILL DEVELOP OVER THE NORTHERN PLAINS AND CANADIAN PRAIRIES SUNDAY AND MONDAY...AND SLOWLY SHIFT EAST ACROSS THE GREAT LAKES THROUGH MIDWEEK. NORTH TO NORTHEAST WINDS WILL BUILD HIGHER WAVES IN SOUTHERN LAKE MICHIGAN THROUGH FRIDAY NIGHT...THEN WINDS WILL SHIFT TO SOUTHERLY ON SATURDAY AND BUILD HIGHER WAVES OVER THE NORTHERN LAKE ZONES THROUGH MONDAY NIGHT. MRC && .LOT WATCHES/WARNINGS/ADVISORIES... IL...BEACH HAZARDS STATEMENT...ILZ014 UNTIL 7 PM FRIDAY. IN...BEACH HAZARDS STATEMENT...INZ001-INZ002 UNTIL 7 PM FRIDAY. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion National Weather Service Lincoln IL 1149 PM CDT Thu Aug 22 2013 .DISCUSSION... ISSUED 900 PM CDT Thu Aug 22 2013 Showers along the cold front have diminished significantly over the last hour, and redevelopment the rest of the night will isolated at best as the front progresses farther south across our forecast area. We diminished pops to just slights in the east and south, but confidence is low than any one location will get additional measurable rain tonight. Clouds will begin to thin out behind the front per satellite trends, which will help fog formation across our northern areas that received rain. We added a mention of some fog for portions of Marshall county to McLean county...where some of our higher rainfall totals were. Temps should have enough time under clearing skies to dip into the low to mid 60s...while southern areas remain clouded and in the upper 60s. Updated the weather and pop grids to the latest trends. The remainder of the forecast grids were in good shape. Updated info will be available shortly. Shimon && .AVIATION... ISSUED 1149 PM CDT Thu Aug 22 2013 A couple of convective updrafts developed along the cold front just southeast of dec in the last hour. MLcape values of 1000-1500 J/kg will keep enough elevated instability in place for a few lightning strikes from the stronger updrafts. Still, coverage will be isolated and we only included a vcts for dec and spi where the front will linger the next few hours. mvfr/ifr fog is expected to develop farther north where skies may clear out under light winds. bmi/cmi were closer to the rainfall from early today...so fog formation may become thicker in those areas. We included tempos for 1sm br 10-13z, but localized 1/4sm fg will be possible toward sunrise. PIA fog may dip to ifr, but the HRRR shows 1/4sm fg for all 3 northern taf sites between 08z and 14z. We did not hit fog that hard yet, but will monitor trends closely. Shimon && .PREV DISCUSSION... ISSUED 230 PM CDT Thu Aug 22 2013 Forecast problem of today is the convection for tonight, and then the warming late in the weekend through the middle of next week. SHORT TERM...Tonight through Saturday night. Frontal zone over northern IL with upper level wave over eastern IA to northern MO. Wave triggered convective complex over northern IL. Airmass over central IL with MUCAPE values around 2500 and number of outflow boundaries has triggered scattered convection over north central cwa, with widely scattered convection in the southeast regions due to the instability. Expect the pcpn to gradually work its way to the south through evening, and in the southeast possible overnight. Boundary should be south of region Friday, and so will be pcpn free. High pressure to keep air a little drier Saturday. LONG TERM...Sunday through Thursday. Upper level ridge start the building process into the our region Sunday. Southerly surface flow will continue hot and humid air moving into region, which will continue through mid week. Will remain dry through forecast period. Goetsch && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1246 PM CDT FRI AUG 23 2013 .UPDATE... ISSUED AT 1240 PM CDT FRI AUG 23 2013 BASED ON TRENDS UP THROUGH MID DAY...THE POTENTIAL FOR ANY DIURNAL CONVECTION IN THE FAR WEST/SOUTHWEST PARTS OF THE CWFA IS BECOMING DOUBTFUL. SATELLITE SHOWS DIURNAL CLOUDS DEVELOPING INDICATING THE BETTER MOISTURE IS GENERALLY WEST OF THE CWFA. ADDITIONALLY...CONVECTIVE TEMPERATURES FROM TRENDS IN THE RAP ARE GENERALLY AT OR ABOVE THE FCST MAX TEMPERATURES FOR THE AFTERNOON. THUS DRY CONDITIONS SHOULD BE SEEN THIS AFTERNOON AND EVENING. ..08.. UPDATE ISSUED AT 1003 AM CDT FRI AUG 23 2013 THE FOG HAS BURNED OFF AND THE LOW CLOUDS WILL CONTINUE LIFT THROUGH EARLY AFTERNOON. RAIN CHANCES DO NOT LOOK OVERLY GREAT FOR THE AFTERNOON HOURS. THE BETTER MOISTURE LIES JUST WEST OF THE CWFA AS DOES THE PROJECTED CONVERGENCE. THE EARLY MORNING FOG HAS ALSO STABILIZED THE WESTERN CWFA SO IT WILL TAKE LONGER TO GENERATE THERMALS. WHAT IS BEING SUGGESTED BY THE MODELS IS ISOLATED TO PERHAPS VERY LOW END SCATTERED SHOWERS AND SOME STORMS IN THE EXTREME WESTERN/SOUTHWEST PARTS OF THE CWFA DURING PEAK HEATING. IF THIS CONVECTION DEVELOPS...IT WILL DISSIPATE WITH SUNSET. ..08.. && .SYNOPSIS... ISSUED AT 318 AM CDT FRI AUG 23 2013 UPPER RIDGE OVER THE SOUTHERN PLAINS DOMINATES THE UPPER PATTERN THIS MORNING...RESULTING IN WEAK NORTHWEST FLOW OVER THE MIDWEST. AT THE SURFACE...A WEAK SURFACE FRONT EXTENDS ACROSS NORTHERN ILLINOIS INTO SOUTHERN IOWA. WIDESPREAD DENSE FOG HAS DEVELOPED ACROSS MUCH OF THE AREA...MAINLY ALONG AND NORTH OF THE HIGHWAY 20 CORRIDOR IN IOWA AND THEN EAST INTO MUCH OF NORTHERN ILLINOIS WHERE 1+ INCHES OF RAIN FELL YESTERDAY. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 318 AM CDT FRI AUG 23 2013 MAIN FORECAST CONCERN TODAY IS FOG THIS MORNING. GIVEN THE EXTENDED DRY SPELL OVER MUCH OF THE AREA...EXPECT FOG TO REMAIN CONCENTRATED IN AREAS WHERE HEAVIER RAIN FELL YESTERDAY. AFTER SUNRISE...MIXING OF THE BOUNDARY LAYER SHOULD MAKE QUICK WORK OF BURNING OFF THE FOG AND HAVE ENDED THE ADVISORY AT 9 AM FOR THIS REASON. ANOTHER MINOR CONCERN IS POSSIBILITY OF SHOWERS THIS AFTERNOON IN WESTERN PORTIONS OF OUR AREA. SHORT RANGE MODELS INDICATING AN AREA OF 850MB MOISTURE SURGING UP THROUGH SOUTH CENTRAL AND SOUTHWEST IOWA THIS AFTERNOON IN THE RETURN FLOW ON THE BACK SIDE OF THE RIDGE. THE RAP IS FARTHER WEST WITH THE MOIST AXIS THAN THE NAM. GIVEN THE STRENGTH OF THE LOW LEVEL RIDGE THAT WILL BE IN PLACE OVER THE AREA THROUGH MID DAY TODAY...THE RAP IS THE MORE LIKELY SOLUTION AND THUS IS FAVORED. HAVE BACKED OFF ON POPS FOR SOUTHWESTERN SECTIONS OF OUR AREA THIS AFTERNOON. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 318 AM CDT FRI AUG 23 2013 UPPER RIDGE BUILDING OVER THE CENTRAL U.S. TO BRING AN EXTENDED PERIOD OF HOT AND DRY WEATHER THAT WILL DOMINATE MOST OF NEXT WEEK. THE ONLY SIGNIFICANT CHANCE FOR PRECIPITATION WILL BE SATURDAY... WHEN A SHORTWAVE TOPPING THE BUILDING UPPER RIDGE MAY INTERACT WITH THE NORTHWARD ADVANCING WARM FRONT TO PRODUCE MAINLY AFTERNOON WIDELY SCATTERED SHOWERS AND THUNDERSTORMS. EVEN THIS POTENTIAL LOOKS RATHER LIMITED DUE TO THE WEAK UPPER FORCING AND AXIS OF PRIMARY LOW LEVEL CONVERGENCE REMAINING WELL WEST OF THE AREA. HAVE THUS KEPT POPS IN THE SLIGHT CHANCE RANGE. LOW LEVEL SOUTHEAST WINDS AND CLOUD COVER WILL LIMIT HIGHS TO THE LOWER 80S NORTH...WHILE THE CENTRAL AND SOUTH SHOULD AGAIN REACH INTO THE MID AND UPPER 80S. SUNDAY THROUGH THURSDAY...HEAT BUILDS OVER THE AREA AS HIGH PRESSURE AT 500 MB SETS UP OVER KS AND MOVES VERY LITTLE THROUGH THE WEEK. OVERALL...THE SYNOPTIC SETUP IS TYPICAL FOR A MID TO LATE SUMMER HEAT WAVE IN THE REGION THAT OFTEN RESULT IN 100 DEGREE PLUS TEMPERATURES WHEN THEY OCCUR IN JULY OR EARLY AUGUST. FOR NOW...WILL NOT FORECAST TEMPERATURES THAT WARM BUT MAY STILL SEE SOME RECORD HIGHS. 850 MB TEMPERATURES ARE SHOWN RISING TO 22 TO 24 C RANGE BY WED...SUPPORTING HIGH TEMPERATURES WELL INTO THE 90S. SUNDAY WILL BE THE COOLEST OF THE STRETCH WITH 850 MB TEMPERATURES SIMILAR TO THE SETUP A COUPLE DAYS AGO THAT RESULTED IN TEMPERATURES TOPPING OUT IN THE UPPER 80S TO AROUND 90. MODELS BEGIN TO DIVERGE ON WED...WHEN THE ECMWF HAS A FLATTER RIDGE THAT MAY ALLOW THE SURFACE BOUNDARY TO SAG BACK SOUTH INTO THE FORECAST AREA...WHICH WOULD RESULT IN COOLER TEMPERATURES AND POSSIBLE RAIN CHANCES. FOR NOW...THE OVERALL MODEL CONSENSUS WILL KEEP A DRY FORECAST WITH HIGHS IN THE LOWER TO MID 90S MON THROUGH THU. HEAT INDEX READINGS WILL OF COURSE BE MUCH HIGHER AND LIKELY REACH ABOVE 100 AND A HEAT ADVISORY MAY BE NEEDED FOR MON THROUGH THU. THESE HEAT INDEX VALUES WILL BE GREATLY DEPENDENT ON DEW POINTS... WHICH ARE OF BELOW AVERAGE CONFIDENCE DUE TO HOW MODELS HANDLE MIXING AND WHETHER THEY EFFECTIVELY CAPTURE THE INCREASINGLY DRY SURFACE CONDITIONS IN PLACE OVER ALL BUT THE NORTHERN THIRD AND FAR EASTERN PORTIONS OF THE FORECAST AREA THAT SAW RAIN THURSDAY. WILL CONTINUE TO MENTION THE EXCESSIVE LATE SEASON HEAT AND POSSIBLE NEED FOR AN ADVISORY IN THE HAZARDOUS WEATHER OUTLOOK. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 1240 PM CDT FRI AUG 23 2013 VFR WX IS EXPECTED THROUGH 06Z/24 AS HIGH PRESSURE REMAINS OVER THE GREAT LAKES. AFT 06Z/24 INCREASING LOW LEVEL MOISTURE SHOULD ALLOW MVFR VSBYS TO DEVELOP PRIOR TO SUNRISE. AFT SUNRISE SATURDAY CONDITIONS WILL AGAIN IMPROVE TO VFR. ..08.. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ UPDATE...08 SYNOPSIS...DMD SHORT TERM...DMD LONG TERM...SHEETS AVIATION...08
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1008 AM CDT FRI AUG 23 2013 .UPDATE... ISSUED AT 1003 AM CDT FRI AUG 23 2013 THE FOG HAS BURNED OFF AND THE LOW CLOUDS WILL CONTINUE LIFT THROUGH EARLY AFTERNOON. RAIN CHANCES DO NOT LOOK OVERLY GREAT FOR THE AFTERNOON HOURS. THE BETTER MOISTURE LIES JUST WEST OF THE CWFA AS DOES THE PROJECTED CONVERGENCE. THE EARLY MORNING FOG HAS ALSO STABILIZED THE WESTERN CWFA SO IT WILL TAKE LONGER TO GENERATE THERMALS. WHAT IS BEING SUGGESTED BY THE MODELS IS ISOLATED TO PERHAPS VERY LOW END SCATTERED SHOWERS AND SOME STORMS IN THE EXTREME WESTERN/SOUTHWEST PARTS OF THE CWFA DURING PEAK HEATING. IF THIS CONVECTION DEVELOPS...IT WILL DISSIPATE WITH SUNSET. ..08.. && .SYNOPSIS... ISSUED AT 318 AM CDT FRI AUG 23 2013 UPPER RIDGE OVER THE SOUTHERN PLAINS DOMINATES THE UPPER PATTERN THIS MORNING...RESULTING IN WEAK NORTHWEST FLOW OVER THE MIDWEST. AT THE SURFACE...A WEAK SURFACE FRONT EXTENDS ACROSS NORTHERN ILLINOIS INTO SOUTHERN IOWA. WIDESPREAD DENSE FOG HAS DEVELOPED ACROSS MUCH OF THE AREA...MAINLY ALONG AND NORTH OF THE HIGHWAY 20 CORRIDOR IN IOWA AND THEN EAST INTO MUCH OF NORTHERN ILLINOIS WHERE 1+ INCHES OF RAIN FELL YESTERDAY. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 318 AM CDT FRI AUG 23 2013 MAIN FORECAST CONCERN TODAY IS FOG THIS MORNING. GIVEN THE EXTENDED DRY SPELL OVER MUCH OF THE AREA...EXPECT FOG TO REMAIN CONCENTRATED IN AREAS WHERE HEAVIER RAIN FELL YESTERDAY. AFTER SUNRISE...MIXING OF THE BOUNDARY LAYER SHOULD MAKE QUICK WORK OF BURNING OFF THE FOG AND HAVE ENDED THE ADVISORY AT 9 AM FOR THIS REASON. ANOTHER MINOR CONCERN IS POSSIBILITY OF SHOWERS THIS AFTERNOON IN WESTERN PORTIONS OF OUR AREA. SHORT RANGE MODELS INDICATING AN AREA OF 850MB MOISTURE SURGING UP THROUGH SOUTH CENTRAL AND SOUTHWEST IOWA THIS AFTERNOON IN THE RETURN FLOW ON THE BACK SIDE OF THE RIDGE. THE RAP IS FARTHER WEST WITH THE MOIST AXIS THAN THE NAM. GIVEN THE STRENGTH OF THE LOW LEVEL RIDGE THAT WILL BE IN PLACE OVER THE AREA THROUGH MID DAY TODAY...THE RAP IS THE MORE LIKELY SOLUTION AND THUS IS FAVORED. HAVE BACKED OFF ON POPS FOR SOUTHWESTERN SECTIONS OF OUR AREA THIS AFTERNOON. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 318 AM CDT FRI AUG 23 2013 UPPER RIDGE BUILDING OVER THE CENTRAL U.S. TO BRING AN EXTENDED PERIOD OF HOT AND DRY WEATHER THAT WILL DOMINATE MOST OF NEXT WEEK. THE ONLY SIGNIFICANT CHANCE FOR PRECIPITATION WILL BE SATURDAY... WHEN A SHORTWAVE TOPPING THE BUILDING UPPER RIDGE MAY INTERACT WITH THE NORTHWARD ADVANCING WARM FRONT TO PRODUCE MAINLY AFTERNOON WIDELY SCATTERED SHOWERS AND THUNDERSTORMS. EVEN THIS POTENTIAL LOOKS RATHER LIMITED DUE TO THE WEAK UPPER FORCING AND AXIS OF PRIMARY LOW LEVEL CONVERGENCE REMAINING WELL WEST OF THE AREA. HAVE THUS KEPT POPS IN THE SLIGHT CHANCE RANGE. LOW LEVEL SOUTHEAST WINDS AND CLOUD COVER WILL LIMIT HIGHS TO THE LOWER 80S NORTH...WHILE THE CENTRAL AND SOUTH SHOULD AGAIN REACH INTO THE MID AND UPPER 80S. SUNDAY THROUGH THURSDAY...HEAT BUILDS OVER THE AREA AS HIGH PRESSURE AT 500 MB SETS UP OVER KS AND MOVES VERY LITTLE THROUGH THE WEEK. OVERALL...THE SYNOPTIC SETUP IS TYPICAL FOR A MID TO LATE SUMMER HEAT WAVE IN THE REGION THAT OFTEN RESULT IN 100 DEGREE PLUS TEMPERATURES WHEN THEY OCCUR IN JULY OR EARLY AUGUST. FOR NOW...WILL NOT FORECAST TEMPERATURES THAT WARM BUT MAY STILL SEE SOME RECORD HIGHS. 850 MB TEMPERATURES ARE SHOWN RISING TO 22 TO 24 C RANGE BY WED...SUPPORTING HIGH TEMPERATURES WELL INTO THE 90S. SUNDAY WILL BE THE COOLEST OF THE STRETCH WITH 850 MB TEMPERATURES SIMILAR TO THE SETUP A COUPLE DAYS AGO THAT RESULTED IN TEMPERATURES TOPPING OUT IN THE UPPER 80S TO AROUND 90. MODELS BEGIN TO DIVERGE ON WED...WHEN THE ECMWF HAS A FLATTER RIDGE THAT MAY ALLOW THE SURFACE BOUNDARY TO SAG BACK SOUTH INTO THE FORECAST AREA...WHICH WOULD RESULT IN COOLER TEMPERATURES AND POSSIBLE RAIN CHANCES. FOR NOW...THE OVERALL MODEL CONSENSUS WILL KEEP A DRY FORECAST WITH HIGHS IN THE LOWER TO MID 90S MON THROUGH THU. HEAT INDEX READINGS WILL OF COURSE BE MUCH HIGHER AND LIKELY REACH ABOVE 100 AND A HEAT ADVISORY MAY BE NEEDED FOR MON THROUGH THU. THESE HEAT INDEX VALUES WILL BE GREATLY DEPENDENT ON DEW POINTS... WHICH ARE OF BELOW AVERAGE CONFIDENCE DUE TO HOW MODELS HANDLE MIXING AND WHETHER THEY EFFECTIVELY CAPTURE THE INCREASINGLY DRY SURFACE CONDITIONS IN PLACE OVER ALL BUT THE NORTHERN THIRD AND FAR EASTERN PORTIONS OF THE FORECAST AREA THAT SAW RAIN THURSDAY. WILL CONTINUE TO MENTION THE EXCESSIVE LATE SEASON HEAT AND POSSIBLE NEED FOR AN ADVISORY IN THE HAZARDOUS WEATHER OUTLOOK. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 627 AM CDT FRI AUG 23 2013 PATCHY DENSE FOG IS AFFECTING AREA TAF SITES THIS MORNING WITH MOST EXPERIENCING IFR OR LIFR CONDITIONS. FOG WILL LIFT RAPIDLY WITHIN THE NEXT 2 HOURS AS THE RISING SUN BEGINS TO PERCOLATE THE BOUNDARY LAYER. ONCE THE FOG LIFTS...EXPECT VFR CONDITIONS WITH SCATTERED AFTERNOON CUMULUS ABOVE 3000FT. OTHERWISE...LIGHT SURFACE WINDS WILL SHIFT TO THE EAST THEN SOUTHEAST THROUGH THE DAY AS THE SURFACE HIGH PRESSURE RIDGE SLIDES EASTWARD ACROSS THE GREAT LAKES. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ UPDATE...08 SYNOPSIS...DMD SHORT TERM...DMD LONG TERM...SHEETS AVIATION...DMD
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
641 AM CDT FRI AUG 23 2013 .SYNOPSIS... ISSUED AT 318 AM CDT FRI AUG 23 2013 UPPER RIDGE OVER THE SOUTHERN PLAINS DOMINATES THE UPPER PATTERN THIS MORNING...RESULTING IN WEAK NORTHWEST FLOW OVER THE MIDWEST. AT THE SURFACE...A WEAK SURFACE FRONT EXTENDS ACROSS NORTHERN ILLINOIS INTO SOUTHERN IOWA. WIDESPREAD DENSE FOG HAS DEVELOPED ACROSS MUCH OF THE AREA...MAINLY ALONG AND NORTH OF THE HIGHWAY 20 CORRIDOR IN IOWA AND THEN EAST INTO MUCH OF NORTHERN ILLINOIS WHERE 1+ INCHES OF RAIN FELL YESTERDAY. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 318 AM CDT FRI AUG 23 2013 MAIN FORECAST CONCERN TODAY IS FOG THIS MORNING. GIVEN THE EXTENDED DRY SPELL OVER MUCH OF THE AREA...EXPECT FOG TO REMAIN CONCENTRATED IN AREAS WHERE HEAVIER RAIN FELL YESTERDAY. AFTER SUNRISE...MIXING OF THE BOUNDARY LAYER SHOULD MAKE QUICK WORK OF BURNING OFF THE FOG AND HAVE ENDED THE ADVISORY AT 9 AM FOR THIS REASON. ANOTHER MINOR CONCERN IS POSSIBILITY OF SHOWERS THIS AFTERNOON IN WESTERN PORTIONS OF OUR AREA. SHORT RANGE MODELS INDICATING AN AREA OF 850MB MOISTURE SURGING UP THROUGH SOUTH CENTRAL AND SOUTHWEST IOWA THIS AFTERNOON IN THE RETURN FLOW ON THE BACK SIDE OF THE RIDGE. THE RAP IS FARTHER WEST WITH THE MOIST AXIS THAN THE NAM. GIVEN THE STRENGTH OF THE LOW LEVEL RIDGE THAT WILL BE IN PLACE OVER THE AREA THROUGH MID DAY TODAY...THE RAP IS THE MORE LIKELY SOLUTION AND THUS IS FAVORED. HAVE BACKED OFF ON POPS FOR SOUTHWESTERN SECTIONS OF OUR AREA THIS AFTERNOON. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 318 AM CDT FRI AUG 23 2013 UPPER RIDGE BUILDING OVER THE CENTRAL U.S. TO BRING AN EXTENDED PERIOD OF HOT AND DRY WEATHER THAT WILL DOMINATE MOST OF NEXT WEEK. THE ONLY SIGNIFICANT CHANCE FOR PRECIPITATION WILL BE SATURDAY... WHEN A SHORTWAVE TOPPING THE BUILDING UPPER RIDGE MAY INTERACT WITH THE NORTHWARD ADVANCING WARM FRONT TO PRODUCE MAINLY AFTERNOON WIDELY SCATTERED SHOWERS AND THUNDERSTORMS. EVEN THIS POTENTIAL LOOKS RATHER LIMITED DUE TO THE WEAK UPPER FORCING AND AXIS OF PRIMARY LOW LEVEL CONVERGENCE REMAINING WELL WEST OF THE AREA. HAVE THUS KEPT POPS IN THE SLIGHT CHANCE RANGE. LOW LEVEL SOUTHEAST WINDS AND CLOUD COVER WILL LIMIT HIGHS TO THE LOWER 80S NORTH...WHILE THE CENTRAL AND SOUTH SHOULD AGAIN REACH INTO THE MID AND UPPER 80S. SUNDAY THROUGH THURSDAY...HEAT BUILDS OVER THE AREA AS HIGH PRESSURE AT 500 MB SETS UP OVER KS AND MOVES VERY LITTLE THROUGH THE WEEK. OVERALL...THE SYNOPTIC SETUP IS TYPICAL FOR A MID TO LATE SUMMER HEAT WAVE IN THE REGION THAT OFTEN RESULT IN 100 DEGREE PLUS TEMPERATURES WHEN THEY OCCUR IN JULY OR EARLY AUGUST. FOR NOW...WILL NOT FORECAST TEMPERATURES THAT WARM BUT MAY STILL SEE SOME RECORD HIGHS. 850 MB TEMPERATURES ARE SHOWN RISING TO 22 TO 24 C RANGE BY WED...SUPPORTING HIGH TEMPERATURES WELL INTO THE 90S. SUNDAY WILL BE THE COOLEST OF THE STRETCH WITH 850 MB TEMPERATURES SIMILAR TO THE SETUP A COUPLE DAYS AGO THAT RESULTED IN TEMPERATURES TOPPING OUT IN THE UPPER 80S TO AROUND 90. MODELS BEGIN TO DIVERGE ON WED...WHEN THE ECMWF HAS A FLATTER RIDGE THAT MAY ALLOW THE SURFACE BOUNDARY TO SAG BACK SOUTH INTO THE FORECAST AREA...WHICH WOULD RESULT IN COOLER TEMPERATURES AND POSSIBLE RAIN CHANCES. FOR NOW...THE OVERALL MODEL CONSENSUS WILL KEEP A DRY FORECAST WITH HIGHS IN THE LOWER TO MID 90S MON THROUGH THU. HEAT INDEX READINGS WILL OF COURSE BE MUCH HIGHER AND LIKELY REACH ABOVE 100 AND A HEAT ADVISORY MAY BE NEEDED FOR MON THROUGH THU. THESE HEAT INDEX VALUES WILL BE GREATLY DEPENDENT ON DEW POINTS... WHICH ARE OF BELOW AVERAGE CONFIDENCE DUE TO HOW MODELS HANDLE MIXING AND WHETHER THEY EFFECTIVELY CAPTURE THE INCREASINGLY DRY SURFACE CONDITIONS IN PLACE OVER ALL BUT THE NORTHERN THIRD AND FAR EASTERN PORTIONS OF THE FORECAST AREA THAT SAW RAIN THURSDAY. WILL CONTINUE TO MENTION THE EXCESSIVE LATE SEASON HEAT AND POSSIBLE NEED FOR AN ADVISORY IN THE HAZARDOUS WEATHER OUTLOOK. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 627 AM CDT FRI AUG 23 2013 PATCHY DENSE FOG IS AFFECTING AREA TAF SITES THIS MORNING WITH MOST EXPERIENCING IFR OR LIFR CONDITIONS. FOG WILL LIFT RAPIDLY WITHIN THE NEXT 2 HOURS AS THE RISING SUN BEGINS TO PERCOLATE THE BOUNDARY LAYER. ONCE THE FOG LIFTS...EXPECT VFR CONDITIONS WITH SCATTERED AFTERNOON CUMULUS ABOVE 3000FT. OTHERWISE...LIGHT SURFACE WINDS WILL SHIFT TO THE EAST THEN SOUTHEAST THROUGH THE DAY AS THE SURFACE HIGH PRESSURE RIDGE SLIDES EASTWARD ACROSS THE GREAT LAKES. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR BENTON- BUCHANAN-CEDAR-CLINTON-DELAWARE-DUBUQUE-JACKSON-JONES-LINN- SCOTT. IL...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR BUREAU- CARROLL-HENRY IL-JO DAVIESS-PUTNAM-ROCK ISLAND-STEPHENSON- WHITESIDE. MO...NONE. && $$ SYNOPSIS...DMD SHORT TERM...DMD LONG TERM...SHEETS AVIATION...DMD
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
319 AM CDT FRI AUG 23 2013 .SYNOPSIS... ISSUED AT 318 AM CDT FRI AUG 23 2013 UPPER RIDGE OVER THE SOUTHERN PLAINS DOMINATES THE UPPER PATTERN THIS MORNING...RESULTING IN WEAK NORTHWEST FLOW OVER THE MIDWEST. AT THE SURFACE...A WEAK SURFACE FRONT EXTENDS ACROSS NORTHERN ILLINOIS INTO SOUTHERN IOWA. WIDESPREAD DENSE FOG HAS DEVELOPED ACROSS MUCH OF THE AREA...MAINLY ALONG AND NORTH OF THE HIGHWAY 20 CORRIDOR IN IOWA AND THEN EAST INTO MUCH OF NORTHERN ILLINOIS WHERE 1+ INCHES OF RAIN FELL YESTERDAY. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 318 AM CDT FRI AUG 23 2013 MAIN FORECAST CONCERN TODAY IS FOG THIS MORNING. GIVEN THE EXTENDED DRY SPELL OVER MUCH OF THE AREA...EXPECT FOG TO REMAIN CONCENTRATED IN AREAS WHERE HEAVIER RAIN FELL YESTERDAY. AFTER SUNRISE...MIXING OF THE BOUNDARY LAYER SHOULD MAKE QUICK WORK OF BURNING OFF THE FOG AND HAVE ENDED THE ADVISORY AT 9 AM FOR THIS REASON. ANOTHER MINOR CONCERN IS POSSIBILITY OF SHOWERS THIS AFTERNOON IN WESTERN PORTIONS OF OUR AREA. SHORT RANGE MODELS INDICATING AN AREA OF 850MB MOISTURE SURGING UP THROUGH SOUTH CENTRAL AND SOUTHWEST IOWA THIS AFTERNOON IN THE RETURN FLOW ON THE BACK SIDE OF THE RIDGE. THE RAP IS FARTHER WEST WITH THE MOIST AXIS THAN THE NAM. GIVEN THE STRENGTH OF THE LOW LEVEL RIDGE THAT WILL BE IN PLACE OVER THE AREA THROUGH MID DAY TODAY...THE RAP IS THE MORE LIKELY SOLUTION AND THUS IS FAVORED. HAVE BACKED OFF ON POPS FOR SOUTHWESTERN SECTIONS OF OUR AREA THIS AFTERNOON. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 318 AM CDT FRI AUG 23 2013 UPPER RIDGE BUILDING OVER THE CENTRAL U.S. TO BRING AN EXTENDED PERIOD OF HOT AND DRY WEATHER THAT WILL DOMINATE MOST OF NEXT WEEK. THE ONLY SIGNIFICANT CHANCE FOR PRECIPITATION WILL BE SATURDAY... WHEN A SHORTWAVE TOPPING THE BUILDING UPPER RIDGE MAY INTERACT WITH THE NORTHWARD ADVANCING WARM FRONT TO PRODUCE MAINLY AFTERNOON WIDELY SCATTERED SHOWERS AND THUNDERSTORMS. EVEN THIS POTENTIAL LOOKS RATHER LIMITED DUE TO THE WEAK UPPER FORCING AND AXIS OF PRIMARY LOW LEVEL CONVERGENCE REMAINING WELL WEST OF THE AREA. HAVE THUS KEPT POPS IN THE SLIGHT CHANCE RANGE. LOW LEVEL SOUTHEAST WINDS AND CLOUD COVER WILL LIMIT HIGHS TO THE LOWER 80S NORTH...WHILE THE CENTRAL AND SOUTH SHOULD AGAIN REACH INTO THE MID AND UPPER 80S. SUNDAY THROUGH THURSDAY...HEAT BUILDS OVER THE AREA AS HIGH PRESSURE AT 500 MB SETS UP OVER KS AND MOVES VERY LITTLE THROUGH THE WEEK. OVERALL...THE SYNOPTIC SETUP IS TYPICAL FOR A MID TO LATE SUMMER HEAT WAVE IN THE REGION THAT OFTEN RESULT IN 100 DEGREE PLUS TEMPERATURES WHEN THEY OCCUR IN JULY OR EARLY AUGUST. FOR NOW...WILL NOT FORECAST TEMPERATURES THAT WARM BUT MAY STILL SEE SOME RECORD HIGHS. 850 MB TEMPERATURES ARE SHOWN RISING TO 22 TO 24 C RANGE BY WED...SUPPORTING HIGH TEMPERATURES WELL INTO THE 90S. SUNDAY WILL BE THE COOLEST OF THE STRETCH WITH 850 MB TEMPERATURES SIMILAR TO THE SETUP A COUPLE DAYS AGO THAT RESULTED IN TEMPERATURES TOPPING OUT IN THE UPPER 80S TO AROUND 90. MODELS BEGIN TO DIVERGE ON WED...WHEN THE ECMWF HAS A FLATTER RIDGE THAT MAY ALLOW THE SURFACE BOUNDARY TO SAG BACK SOUTH INTO THE FORECAST AREA...WHICH WOULD RESULT IN COOLER TEMPERATURES AND POSSIBLE RAIN CHANCES. FOR NOW...THE OVERALL MODEL CONSENSUS WILL KEEP A DRY FORECAST WITH HIGHS IN THE LOWER TO MID 90S MON THROUGH THU. HEAT INDEX READINGS WILL OF COURSE BE MUCH HIGHER AND LIKELY REACH ABOVE 100 AND A HEAT ADVISORY MAY BE NEEDED FOR MON THROUGH THU. THESE HEAT INDEX VALUES WILL BE GREATLY DEPENDENT ON DEWPOINTS... WHICH ARE OF BELOW AVERAGE CONFIDENCE DUE TO HOW MODELS HANDLE MIXING AND WHETHER THEY EFFECTIVELY CAPTURE THE INCREASINGLY DRY SURFACE CONDITIONS IN PLACE OVER ALL BUT THE NORTHERN THIRD AND FAR EASTERN PORTIONS OF THE FORECAST AREA THAT SAW RAIN THURSDAY. WILL CONTINUE TO MENTION THE EXCESSIVE LATE SEASON HEAT AND POSSIBLE NEED FOR AN ADVISORY IN THE HAZARDOUS WEATHER OUTLOOK. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 1145 PM CDT THU AUG 22 2013 ABUNDANT LOW LEVEL MOISTURE...MAINLY CLEAR SKIES AND LIGHT WINDS WILL CONTINUE TO PROMOTE SOME STRATUS AND FOG DEVELOPMENT OVERNIGHT UNTIL MID MORNING. SHALLOW STEEP LOW LEVEL INVERSION SUPPORTIVE OF VSBYS BEING QUITE VARIABLE 1-5SM... WITH SOME PATCHY 1/4-1/2SM. HAVE CONTINUED WITH THE LOWEST VSBYS OF LIFR AT KDBQ DUE TO WET GROUND FROM RECENT RAINS. CANT RULE OUT VLIFR THOUGH AT KDBQ... AND SOME OF THE LATEST HI-RES GUIDANCE CONTINUES TO SUGGEST LIFR/VLIFR MORE WIDESPREAD ALSO AFFECTING KCID...KMLI AND KBRL BUT HELD OFF ON MENTION AT THESE TAF SITES DUE TO LOWER CONFIDENCE. ALSO...AREAS OF MVFR CIGS MOST PREVALENT AT KBRL OVERNIGHT WHERE THE HIGHER SURFACE DEWPTS ARE LOCATED. COULD SEE A BRIEF PERIOD OF MVFR CIGS AT ALL SITES DEVELOP BY MID MORNING WITH HEATING OF LOW LEVEL MOISTURE...BUT ANY LOW CLOUDS AND FOG TO LIFT BY 18Z WITH VFR CONDITIONS THEREAFTER AS WINDS INCREASE FROM THE E/SE AT 5-10 KTS. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR BUCHANAN- CLINTON-DELAWARE-DUBUQUE-JACKSON-JONES. IL...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR BUREAU- CARROLL-JO DAVIESS-PUTNAM-STEPHENSON-WHITESIDE. MO...NONE. && $$ SYNOPSIS...DMD SHORT TERM...DMD LONG TERM...SHEETS AVIATION...05
AREA FORECAST DISCUSSION...UPDATED
NWS DODGE CITY KS
549 PM CDT Fri Aug 23 2013 ...Updated for Aviation... .SYNOPSIS... ISSUED AT 1208 PM CDT FRI AUG 23 2013 At 12z Friday a 500mb trough was located over northern California and the pacific northwest. A 500mb high was located across western Oklahoma. An upper level ridge axis extended from this upper high northward into south central Canada. 700mb temperatures at 12z this morning across the central high plains ranged from 11c at Dodge City and North Platte to +16c at Denver. A 850mb BAROCLINIC zone extended from southwest Nebraska to northeast Oklahoma. && .SHORT TERM...(This evening through Saturday) ISSUED AT 202 PM CDT FRI AUG 23 2013 Water Vapor loop indicating an upper level disturbance was moving north across east central Colorado earlier this morning. The 12z RAP, NAM,and GFS 400-450mb potential vorticity field picked up on this feature fairly well and currently moves this feature across northern Kansas early this evening. NAM and to a lesser degree RAP and HRRR even hints at some precipitation this evening near and north of I70 as this wave passes. Given the late day instability expected ahead of this wave the chance for an isolated thunderstorm or two can not be ruled out...especially near the Nebraska border. At this time am leaning towards leaving mention of thunderstorms out of the forecast near the interstate 70 corridor given the better instability and forcing is forecast to be further north. Will however insert a mention of isolated thunderstorms if convection appears to be developing further south than anticipated. Skies are expected to clear from west to east as this upper wave passes north central Kansas after midnight. Given surface dewpoints in the 60s and surface winds at 10kts will stay close to the previous forecast with overnight ranging from the mid 60s in far western Kansas to around 70 in north central and south central Kansas. On Saturday an upper high will slowly move east across southwest Kansas and 800mb temperatures at 00z Sunday are forecast range from 24c to 28c. This suggests highs Saturday afternoon mainly in the mid 90s given full sun. .LONG TERM...(Saturday night through Friday) ISSUED AT 340 PM CDT FRI AUG 23 2013 The medium range forecast models continue to develop a large broad upper height ridge across the central section of the nation through next weekend. This will promote large scale subsidence aloft and southerly surface winds across western Kansas. Although technically not zero percent, very little chance for convection is expected during this period. The only opportunity for convection would be late evening or overnight near the Colorado line as localized high terrain convection can feed on steep mid level lapse rates far enough east. The flow however doesn`t support this. Beside the lack of precipitation, the period will be marked by a few breezy to marginally windy days and very warm conditions. High surface pressure across the eastern states will setup a pressure gradient to the lee of the Rockies creating diurnally mixed out gusty south winds. The models in addition to the MOS products have trended temperatures warmer in recent runs. Highs during the period will likely be at least 5 degrees to as much as 10 degrees warmer than normal. Persistence or intensification of the drought conditions are expected to the west of highway 283. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) ISSUED AT 545 PM CDT FRI AUG 23 2013 VFR conditions will continue into Saturday with light south to southeast winds increasing to 15-25kt after 15-17Z. && .PRELIMINARY POINT TEMPS/POPS... DDC 68 95 72 96 / 0 0 0 0 GCK 67 96 71 96 / 0 0 0 0 EHA 66 94 70 94 / 0 0 0 0 LBL 66 96 72 96 / 0 0 0 0 HYS 70 96 72 97 / 10 0 0 0 P28 71 95 73 96 / 0 0 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...Burgert SHORT TERM...Burgert LONG TERM...Russell AVIATION...Kruse
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
341 PM CDT Fri Aug 23 2013 ...UPDATED LONG TERM... .SYNOPSIS... ISSUED AT 1208 PM CDT FRI AUG 23 2013 At 12z Friday a 500mb trough was located over northern California and the pacific northwest. A 500mb high was located across western Oklahoma. An upper level ridge axis extended from this upper high northward into south central Canada. 700mb temperatures at 12z this morning across the central high plains ranged from 11c at Dodge City and North Platte to +16c at Denver. A 850mb baroclinic zone extended from southwest Nebraska to northeast Oklahoma. && .SHORT TERM...(This evening through Saturday) ISSUED AT 202 PM CDT FRI AUG 23 2013 Water Vapor loop indicating an upper level disturbance was moving north across east central Colorado earlier this morning. The 12z RAP, NAM,and GFS 400-450mb potential vorticity field picked up on this feature fairly well and currently moves this feature across northern Kansas early this evening. NAM and to a lesser degree RAP and HRRR even hints at some precipitation this evening near and north of I70 as this wave passes. Given the late day instability expected ahead of this wave the chance for an isolated thunderstorm or two can not be ruled out...especially near the Nebraska border. At this time am leaning towards leaving mention of thunderstorms out of the forecast near the interstate 70 corridor given the better instability and forcing is forecast to be further north. Will however insert a mention of isolated thunderstorms if convection appears to be developing further south than anticipated. Skies are expected to clear from west to east as this upper wave passes north central Kansas after midnight. Given surface dewpoints in the 60s and surface winds at 10kts will stay close to the previous forecast with overnight ranging from the mid 60s in far western Kansas to around 70 in north central and south central Kansas. On Saturday an upper high will slowly move east across southwest Kansas and 800mb temperatures at 00z Sunday are forecast range from 24c to 28c. This suggests highs Saturday afternoon mainly in the mid 90s given full sun. .LONG TERM...(Saturday night through Friday) ISSUED AT 340 PM CDT FRI AUG 23 2013 The medium range forecast models continue to develop a large broad upper height ridge across the central section of the nation through next weekend. This will promote large scale subsidence aloft and southerly surface winds across western Kansas. Although technically not zero percent, very little chance for convection is expected during this period. The only opportunity for convection would be late evening or overnight near the Colorado line as localized high terrain convection can feed on steep mid level lapse rates far enough east. The flow however doesn`t support this. Beside the lack of precipitation, the period will be marked by a few breezy to marginally windy days and very warm conditions. High surface pressure across the eastern states will setup a pressure gradient to the lee of the Rockies creating diurnally mixed out gusty south winds. The models in addition to the MOS products have trended temperatures warmer in recent runs. Highs during the period will likely be at least 5 degrees to as much as 10 degrees warmer than normal. Persistence or intensification of the drought conditions are expected to the west of highway 283. && .AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon) ISSUED AT 1208 PM CDT FRI AUG 23 2013 VFR conditions can be expected through tonight at all TAF sites. As surface troughing persist on the lee side of the Rockies, winds will remain southerly this afternoon and evening from 10 to 15 kt. A few gusts around 25 kt could be possible this afternoon. && .PRELIMINARY POINT TEMPS/POPS... DDC 68 95 72 96 / 0 0 0 0 GCK 67 96 71 96 / 0 0 0 0 EHA 66 94 70 94 / 0 0 0 0 LBL 66 96 72 96 / 0 0 0 0 HYS 70 96 72 97 / 10 0 0 0 P28 71 95 73 96 / 0 0 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...Burgert SHORT TERM...Burgert LONG TERM...Russell AVIATION...Scott
AREA FORECAST DISCUSSION
NWS GOODLAND KS
158 PM MDT FRI AUG 23 2013 .UPDATE... ISSUED AT 559 AM MDT FRI AUG 23 2013 JUST FINISHED QUICK UPDATE TO POP/WX TO REFLECT CURRENT COVERAGE OF SHOWERS/THUNDERSTORMS IN EASTER CWA. ALSO LINGERING SLIGHT CHANCE POPS IN NORTHERN CWA THROUGH DAY TO ACCOUNT FOR POSSIBLE SHOWERS/THUNDERSTORMS REDEVELOPING AS MESO-LOW FROM OVERNIGHT CONVECTION OVER NE COLORADO SLOWLY MOVES OVER CWA. THERE APPEARS TO BE SOME REFLECTION AT H7-H5 FROM RAP WITH THIS FEATURE. LATEST HRRR WOULD ACTUALLY SUPPORT BETTER COVERAGE AFTER SUNRISE...HOWEVER WITH VERY LITTLE RETURNS YET THIS MORNING WILL STAY CONSERVATIVE WITH THIS UPDATE. && .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 251 AM MDT FRI AUG 23 2013 LATEST WV IMAGERY AND H5 ANALYSIS SHOWS LARGE SCALE RIDGE OVER THE CENTRAL US...CENTERED OVER THE SOUTHERN PLAINS. A STALLED FRONT EXTENDS SOUTH ALONG THE FRONT RANGE IN COLORADO AND BACK TO THE EAST AS A WARM FRONT OVER THE SOUTHERN HALF OF OUR CWA. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS HAVE DEVELOPED EARLY THIS MORNING ACROSS OUR CWA AS A WARM FRONT HAS LIFTED NORTH WITH GOOD MOISTURE AND MARGINAL INSTABILITY IN PLACE...AND SUPPORT FROM LLJ/MID LEVEL THETA-E CONVERGENCE. SHORT RANGE GUIDANCE HAS DECENT HANDLE ON SHOWERS/THUNDERSTORMS IN EASTERN COLORADO...HOWEVER IS NOT DOING A GOOD JOB WITH ACTIVITY ALONG FRONT ACROSS REST OF CWA. WHILE CHANCE OF MEASURABLE IS NOT AS GREAT...COVERAGE ON RADAR HAS INCREASED QUITE A BIT OVER THE LAST FEW HOURS...SO I WENT AHEAD AND INCREASE POPS TO CHANCE CATEGORY. IVE TRENDED THIS ACTIVITY NORTHWARD THROUGH SUNRISE BASED ON TIMING OF FRONT. I COULD NT RULE OUT ACTIVITY POSSIBLY LINGERING THROUGH MID MORNING...HOWEVER IT APPEARS BEST ISENTROPIC SUPPORT AND FORCING WILL BE NORTH OF OUR CWA BY THAT POINT. WILL NEED TO MONITOR SHORT TERM TRENDS. OTHER IMMEDIATE CONCERN IS POSSIBILITY OF FOG DEVELOPMENT. THERE HAS BE LIGHT FOG REPORTED OVER PARTS OF SW NEBRASKA...AND WITH VERY GOOD BL MOISTURE I COULD NT RULE OUT ADDITIONAL FOG DEVELOPMENT FURTHER SOUTH. THE INHIBITING FACTOR WILL BE INSULATION FROM CLOUD COVER AND LESS FAVORABLE BL CONDITIONS BEHIND LIFTING WARM FRONT. HAVE KEPT PATCHY FOG MENTION ACROSS NORTHERN PART OF CWA THIS MORNING. AFTER PRECIP ENDS THIS MORNING FORECAST SHOULD REMAIN DRY THROUGH SUNDAY WITH H5 RIDGE STRENGTHENING...LARGE SCALE SUBSIDENCE OVER OUR CWA...AND MEAN STORM TRACK SHIFTING NORTH. LEE TROUGH WILL STRENGTHEN BY THIS WEEKEND WITH HOT AND BREEZY CONDITIONS EACH AFTERNOON. VERY LITTLE DIFFERENCE REGARDING AIR MASS OVER OUR CWA...WITH H85 TEMPS IN THE 28-31C RANGE SUPPORTING HIGHS IN THE UPPER 90S/NEAR 100F. SAW LITTLE REASON TO DEVIATE FROM PREVIOUS FORECAST WHICH HAD GOOD HANDLE ON MODEL TRENDS. DEPENDING ON AFTERNOON MIXING WE COULD SEE RH VALUES APPROACH RED FLAG CRITERIA IN THE WEST SAT/SUN. AT THIS POINT IT DOES NT APPEAR THAT WE WILL SEE THE WIND/RH CROSSOVER NECESSARY FOR HIGHLIGHTS...BUT WE WILL NEED TO MONITOR. .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 158 PM MDT FRI AUG 23 2013 SATURDAY NIGHT-MONDAY...596 DM H5 RIDGE WILL BE THE DOMINANT FEATURE IN PLACE ACROSS MUCH OF THE AREA WITH THE RIDGE CENTER EXPECTED TO GRADUALLY RETROGRADE THROUGH THE PERIOD. PRESENCE OF LARGE AREA OF SUBSIDENCE AND ONLY WEAK AFTERNOON INSTABILITY PROFILES LEADS ME TO THINK QUIET WEATHER WILL CONTINUE THROUGH THE PERIOD WITH MAIN AREA OF CONCERNS BEING TEMPERATURES AND POSSIBLY FIRE WEATHER CONCERNS WITH THE DRY CONDITIONS. TEMPERATURES WILL WARM THROUGH THE PERIOD WITH SFC TROUGH EXPECTED TO KEEP WINDS UP DURING THE OVERNIGHT HOURS WHICH WILL GIVE TEMPERATURES A RUNNING START EACH DAY AS RADIATIONAL COOLING WILL BE SOMEWHAT INHIBITED. LOOKS LIKE MID/UPPER 90S TO NEAR 100 CAN BE EXPECTED BY MONDAY ALTHOUGH RECENT VERIFICATION INDICATES VARIOUS TEMP FORECASTS HAVE BEEN ON THE WARM SIDE THINGS WHICH DOES LOWER CONFIDENCE A BIT. GUSTY SOUTHERLY WINDS EXPECTED EACH AFTERNOON AS SFC TROUGH REMAINS NEARLY STATIONARY. WARM TEMPS WILL HELP PUSH HUMIDITIES DOWN TO AROUND 20 PERCENT...BUT MIXED LEVEL FORECASTS DO NOT SUPPORT A STRONG DROP IN DEWPOINTS AT THIS TIME SO POTENTIAL FOR A CRITICAL FIRE WEATHER DAY APPEAR TO BE LOW. IN THE EXTENDED (MON NIGHT-FRI)...GENERAL CONSENSUS OF MEDIUM RANGE MODELS SUPPORTS STRONG H5 RIDGE RETROGRADING SLIGHTLY WITH RIDGE CENTER NEARING THE CWA AND PERSISTING THERE THROUGH THE WEEK. CONTINUED WARM AND DRY CONDITIONS CAN BE EXPECTED AND WILL HAVE TO WATCH WIND SPEEDS CLOSELY AS HUMIDITIES WILL NEAR CRITICAL FIRE WEATHER VALUES EACH AFTERNOON. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 1100 AM MDT FRI AUG 23 2013 VFR CONDITIONS EXPECTED AT KGLD AND KMCK. A MESOSCALE CONVECTIVE VORTICE...LEFTOVER FROM SHOWERS AND THUNDERSTORMS ACROSS THE COLORADO FRONT RANGE YESTERDAY...IS SPINNING OVER THE AREA THIS MORNING. THIS SYSTEM IS EXPECTED TO CONTINUE TO SLOWLY MOVE EAST/NORTHEAST THROUGH THE REST OF THE DAY EXITING THE AREA EARLY TONIGHT. THE COMBINATION OF DIURNAL HEATING AND THIS DISTURBANCE SHOULD PRODUCE SOME SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EARLY EVENING. MOST LIKELY LOCATION TO POTENTIALLY BE IMPACTED WOULD BE KMCK. HOWEVER...CONFIDENCE NOT HIGH ENOUGH TO INCLUDE IN TAF AT PRESENT TIME. OTHERWISE...BOTH TERMINALS CAN EXPECT AN INCREASE IN WINDS THIS AFTERNOON AND EVENING WHERE GUSTS AROUND 20KTS POSSIBLE. SOUTHERLY WINDS WILL INCREASE IN SPEED DURING THE DAY SATURDAY WITH GUSTS OF 25-30KTS POSSIBLE AT BOTH TERMINALS. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...DR SHORT TERM...DR LONG TERM...JRM AVIATION...99
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
204 PM CDT Fri Aug 23 2013 ...Updated Short term discussion... .SYNOPSIS... ISSUED AT 1208 PM CDT FRI AUG 23 2013 At 12z Friday a 500mb trough was located over northern California and the pacific northwest. A 500mb high was located across western Oklahoma. An upper level ridge axis extended from this upper high northward into south central Canada. 700mb temperatures at 12z this morning across the central high plains ranged from 11c at Dodge City and North Platte to +16c at Denver. A 850mb baroclinic zone extended from southwest Nebraska to northeast Oklahoma. && .SHORT TERM...(This evening through Saturday) ISSUED AT 202 PM CDT FRI AUG 23 2013 Water Vapor loop indicating an upper level disturbance was moving north across east central Colorado earlier this morning. The 12z RAP, NAM,and GFS 400-450mb potential vorticity field picked up on this feature fairly well and currently moves this feature across northern Kansas early this evening. NAM and to a lesser degree RAP and HRRR even hints at some precipitation this evening near and north of I70 as this wave passes. Given the late day instability expected ahead of this wave the chance for an isolated thunderstorm or two can not be ruled out...especially near the Nebraska border. At this time am leaning towards leaving mention of thunderstorms out of the forecast near the interstate 70 corridor given the better instability and forcing is forecast to be further north. Will however insert a mention of isolated thunderstorms if convection appears to be developing further south than anticipated. Skies are expected to clear from west to east as this upper wave passes north central Kansas after midnight. Given surface dewpoints in the 60s and surface winds at 10kts will stay close to the previous forecast with overnight ranging from the mid 60s in far western Kansas to around 70 in north central and south central Kansas. On Saturday an upper high will slowly move east across southwest Kansas and 800mb temperatures at 00z Sunday are forecast range from 24c to 28c. This suggests highs Saturday afternoon mainly in the mid 90s given full sun. .LONG TERM...(Saturday through Thursday) ISSUED AT 226 AM CDT FRI AUG 23 2013 For the extended period from Saturday night through next Friday, very little has change has shown up in the medium and long range models. A upper level high pressure area will essentially be anchored over the Sunflower State through the foreseeable future. This upper high will bring a lot of sunshine to western Kansas, resulting in afternoon highs in the mid to upper 90s. Will the 100F degree mark be reached? Possibly by Wednesday or beyond. The prolonged pattern of upper high pressure and a long southwest fetch of warming winds at the surface may be just enough for a couple of spots in western Kansas to peak near or over 100F. For now, have accepted what the CR_Extended tool produced, with 97F-98F max temps ranges. The only clouds expected through Friday are mid and high level in nature. These clouds will not alter or slow down the surface heating. Furthermore, a lee side trough will form each afternoon across eastern Colorado, and will edge eastward nearly every day into western Kansas. Unfortunately, there will be little or no substantial moisture to work with, and thus there are no precipitation chances included in the extended period. Minimum temperatures will basically be in the lower to mid 70s, but creep slowly upward with time. By Friday, expect lows in the mid 70s in our eastern zones of Barber, Comanche and Pratt counties, and around the 70F degree mark along the Colorado border. In general, winds will be from the south to southwest, dipping to 10 to 15 mph overnight, and then increasing by late mornings into the 15 to 25 mph and gusty range. && .AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon) ISSUED AT 1208 PM CDT FRI AUG 23 2013 VFR conditions can be expected through tonight at all TAF sites. As surface troughing persist on the lee side of the Rockies, winds will remain southerly this afternoon and evening from 10 to 15 kt. A few gusts around 25 kt could be possible this afternoon. && .PRELIMINARY POINT TEMPS/POPS... DDC 69 94 72 94 / 0 0 0 0 GCK 68 94 71 95 / 0 0 0 0 EHA 64 94 70 93 / 0 0 0 0 LBL 67 95 72 95 / 0 0 0 0 HYS 70 94 72 95 / 0 0 0 0 P28 71 94 73 94 / 0 0 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...Burgert SHORT TERM...Burgert LONG TERM...Burke AVIATION...Scott
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1220 PM CDT Fri Aug 23 2013 .SHORT TERM...(Today and Tonight) Issued at 335 AM CDT FRI AUG 23 2013 A broad upper level ridge of high pressure will be centered over the state of Kansas for the next 24 hours. early this morning, elevated showers were developing due to weak isentropic lift north of an old outflow boundary across west central KS. At this time I think the showers should remain just west of the cwa...though some isolated showers may develop near sunrise across the southwest and northern counties of the CWA, but should dissipate by mid morning. May place a 10 to 14 pop across the southwest and northern counties in case any isolated showers develop. Widespread convection along the foothills of CO will cause periods of high clouds to move across the CWA Today. The 06Z NAM is the only numerical model that breaks out deep moist convection across north central KS late this afternoon and into the early evening hours. The NAM may be trying to bring the MCV from the CO foothill convective complex too far south across the center of the H5 ridge axis. The GFS, arw, nmm and RAP show the the mcv rotating farther northeast across western and central NE and show no qpf developing across north central KS this afternoon. Just in case the NAM solution may be accurate I inserted 10 to 14 pops for late this afternoon and early evening across the northwest counties of the CWA. High temperatures Today may be dependent on the amount of high clouds. if the high clouds thin out this afternoon then highs will reach into the lower to mid 90s. If we keep a thicker veil of high clouds through the afternoon hours, then highs may only reach the upper 80s to around 90. Tonight, if any showers or isolated thunderstorms develop across north central KS they should dissipate after sunset. skies should become mostly clear through the night. overnight lows will drop into the upper 60s to lower 70s. .LONG TERM...(Saturday through Thursday) Issued at 335 AM CDT FRI AUG 23 2013 Medium range models are very similar in building upper ridge eastward through the weekend with axis over MO before retrogressing slightly and amplifying across KS through most of next week. This will allow for only weak inhibition by peak heating over the weekend...but a strengthening cap into next week. However with the exception of diurnal heating...no significant forcing evident to warrant any pops at this point...and even less confidence into next week. Therefore will keep the fcst through the extended dry. The llvl thermal fields only warm slightly from the weekend into the middle of next week...so the current fcst of only minor high temp increases thru the middle 90s into next week looks good for now. There is some concern that soil conditions steadily drying out and some hint of more veering llvl windfields by the middle of next week could lead to higher temps in the western cwa. A slight increase in dewpoints into next week with the slightly warmer temps should inch heat indices to around the century mark for most areas through next week. && .AVIATION...(For the 18Z TAFs through 18Z Saturday Afternoon) Issued at 1216 PM CDT FRI AUG 23 2013 Will keep vfr conditions through the period and monitor for some outside chances for convection toward the end of the taf cycle, but at this time seems to stay north of the terminals. 67 && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Gargan LONG TERM...63 AVIATION...67
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1100 AM MDT FRI AUG 23 2013 .UPDATE... ISSUED AT 559 AM MDT FRI AUG 23 2013 JUST FINISHED QUICK UPDATE TO POP/WX TO REFLECT CURRENT COVERAGE OF SHOWERS/THUNDERSTORMS IN EASTER CWA. ALSO LINGERING SLIGHT CHANCE POPS IN NORTHERN CWA THROUGH DAY TO ACCOUNT FOR POSSIBLE SHOWERS/THUNDERSTORMS REDEVELOPING AS MESO-LOW FROM OVERNIGHT CONVECTION OVER NE COLORADO SLOWLY MOVES OVER CWA. THERE APPEARS TO BE SOME REFLECTION AT H7-H5 FROM RAP WITH THIS FEATURE. LATEST HRRR WOULD ACTUALLY SUPPORT BETTER COVERAGE AFTER SUNRISE...HOWEVER WITH VERY LITTLE RETURNS YET THIS MORNING WILL STAY CONSERVATIVE WITH THIS UPDATE. && .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 251 AM MDT FRI AUG 23 2013 LATEST WV IMAGERY AND H5 ANALYSIS SHOWS LARGE SCALE RIDGE OVER THE CENTRAL US...CENTERED OVER THE SOUTHERN PLAINS. A STALLED FRONT EXTENDS SOUTH ALONG THE FRONT RANGE IN COLORADO AND BACK TO THE EAST AS A WARM FRONT OVER THE SOUTHERN HALF OF OUR CWA. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS HAVE DEVELOPED EARLY THIS MORNING ACROSS OUR CWA AS A WARM FRONT HAS LIFTED NORTH WITH GOOD MOISTURE AND MARGINAL INSTABILITY IN PLACE...AND SUPPORT FROM LLJ/MID LEVEL THETA-E CONVERGENCE. SHORT RANGE GUIDANCE HAS DECENT HANDLE ON SHOWERS/THUNDERSTORMS IN EASTERN COLORADO...HOWEVER IS NOT DOING A GOOD JOB WITH ACTIVITY ALONG FRONT ACROSS REST OF CWA. WHILE CHANCE OF MEASURABLE IS NOT AS GREAT...COVERAGE ON RADAR HAS INCREASED QUITE A BIT OVER THE LAST FEW HOURS...SO I WENT AHEAD AND INCREASE POPS TO CHANCE CATEGORY. IVE TRENDED THIS ACTIVITY NORTHWARD THROUGH SUNRISE BASED ON TIMING OF FRONT. I COULD NT RULE OUT ACTIVITY POSSIBLY LINGERING THROUGH MID MORNING...HOWEVER IT APPEARS BEST ISENTROPIC SUPPORT AND FORCING WILL BE NORTH OF OUR CWA BY THAT POINT. WILL NEED TO MONITOR SHORT TERM TRENDS. OTHER IMMEDIATE CONCERN IS POSSIBILITY OF FOG DEVELOPMENT. THERE HAS BE LIGHT FOG REPORTED OVER PARTS OF SW NEBRASKA...AND WITH VERY GOOD BL MOISTURE I COULD NT RULE OUT ADDITIONAL FOG DEVELOPMENT FURTHER SOUTH. THE INHIBITING FACTOR WILL BE INSULATION FROM CLOUD COVER AND LESS FAVORABLE BL CONDITIONS BEHIND LIFTING WARM FRONT. HAVE KEPT PATCHY FOG MENTION ACROSS NORTHERN PART OF CWA THIS MORNING. AFTER PRECIP ENDS THIS MORNING FORECAST SHOULD REMAIN DRY THROUGH SUNDAY WITH H5 RIDGE STRENGTHENING...LARGE SCALE SUBSIDENCE OVER OUR CWA...AND MEAN STORM TRACK SHIFTING NORTH. LEE TROUGH WILL STRENGTHEN BY THIS WEEKEND WITH HOT AND BREEZY CONDITIONS EACH AFTERNOON. VERY LITTLE DIFFERENCE REGARDING AIR MASS OVER OUR CWA...WITH H85 TEMPS IN THE 28-31C RANGE SUPPORTING HIGHS IN THE UPPER 90S/NEAR 100F. SAW LITTLE REASON TO DEVIATE FROM PREVIOUS FORECAST WHICH HAD GOOD HANDLE ON MODEL TRENDS. DEPENDING ON AFTERNOON MIXING WE COULD SEE RH VALUES APPROACH RED FLAG CRITERIA IN THE WEST SAT/SUN. AT THIS POINT IT DOES NT APPEAR THAT WE WILL SEE THE WIND/RH CROSSOVER NECESSARY FOR HIGHLIGHTS...BUT WE WILL NEED TO MONITOR. .LONG TERM...(MONDAY THROUGH THURSDAY) ISSUED AT 251 AM MDT FRI AUG 23 2013 WHILE THE PAST FEW EXTENDED RANGE FORECASTS HAVE SOUNDED LIKE A BROKEN RECORD - HOT AND DRY - IT APPEARS AN END IS IN SIGHT. EARLY NEXT WEEK AN UPPER LEVEL RIDGE WILL BE CENTERED OVER KANSAS...WITH A A NORTH-SOUTH ORIENTED SURFACE TROUGH DEVELOP ALONG EASTERN COLORADO. THE ECMWF HAD PREVIOUSLY BEEN A BIT MORE CONSERVATIVE WITH TEMPS BUT NOW HAS COME AROUND TO BETTER MATCH THE GFS AND GEM WITH TEMPS IN THE LOW 30S C...TRANSLATING TO MID TO UPPER 90S IN THE FIRST HALF OF THE WEEK. TRIPLE-DIGIT TEMPS LOOK ALMOST LIKELY ON MONDAY AND TUESDAY FOR THE NORMAL HOT SPOTS...PLACES LIKE TRIBUNE...HILL CITY...AND MCCOOK...APPROACHING /BUT PROBABLY NOT EXCEEDING/ RECORDS IN SOME SPOTS. LATER IN THE WEEK THE RIDGE WILL SLOWLY NUDGE FARTHER EAST BRINGING RELIEF TO THE HEAT...SOMETHING THE OPERATIONAL GFS IS A BIT SLOW TO REALIZE BUT THE GEFS MEAN AND ECMWF HAVE BEEN CONSISTENT WITH THE PAST FEW RUNS. PRECIP CHANCES ARE NEAR NIL WITH THE RIDGE OVER US...BUT AS IT MOVES EAST WE COULD SEE CHANCES INCREASE TOWARDS THE WEEKEND. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 1100 AM MDT FRI AUG 23 2013 VFR CONDITIONS EXPECTED AT KGLD AND KMCK. A MESOSCALE CONVECTIVE VORTICE...LEFTOVER FROM SHOWERS AND THUNDERSTORMS ACROSS THE COLORADO FRONT RANGE YESTERDAY...IS SPINNING OVER THE AREA THIS MORNING. THIS SYSTEM IS EXPECTED TO CONTINUE TO SLOWLY MOVE EAST/NORTHEAST THROUGH THE REST OF THE DAY EXITING THE AREA EARLY TONIGHT. THE COMBINATION OF DIURNAL HEATING AND THIS DISTURBANCE SHOULD PRODUCE SOME SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EARLY EVENING. MOST LIKELY LOCATION TO POTENTIALLY BE IMPACTED WOULD BE KMCK. HOWEVER...CONFIDENCE NOT HIGH ENOUGH TO INCLUDE IN TAF AT PRESENT TIME. OTHERWISE...BOTH TERMINALS CAN EXPECT AN INCREASE IN WINDS THIS AFTERNOON AND EVENING WHERE GUSTS AROUND 20KTS POSSIBLE. SOUTHERLY WINDS WILL INCREASE IN SPEED DURING THE DAY SATURDAY WITH GUSTS OF 25-30KTS POSSIBLE AT BOTH TERMINALS. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...DR SHORT TERM...DR LONG TERM...JJM AVIATION...99
AREA FORECAST DISCUSSION
NWS GOODLAND KS
605 AM MDT FRI AUG 23 2013 .UPDATE... ISSUED AT 559 AM MDT FRI AUG 23 2013 JUST FINISHED QUICK UPDATE TO POP/WX TO REFLECT CURRENT COVERAGE OF SHOWERS/THUNDERSTORMS IN EASTER CWA. ALSO LINGERING SLIGHT CHANCE POPS IN NORTHERN CWA THROUGH DAY TO ACCOUNT FOR POSSIBLE SHOWERS/THUNDERSTORMS REDEVELOPING AS MESO-LOW FROM OVERNIGHT CONVECTION OVER NE COLORADO SLOWLY MOVES OVER CWA. THERE APPEARS TO BE SOME REFLECTION AT H7-H5 FROM RAP WITH THIS FEATURE. LATEST HRRR WOULD ACTUALLY SUPPORT BETTER COVERAGE AFTER SUNRISE...HOWEVER WITH VERY LITTLE RETURNS YET THIS MORNING WILL STAY CONSERVATIVE WITH THIS UPDATE. && .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 251 AM MDT FRI AUG 23 2013 LATEST WV IMAGERY AND H5 ANALYSIS SHOWS LARGE SCALE RIDGE OVER THE CENTRAL US...CENTERED OVER THE SOUTHERN PLAINS. A STALLED FRONT EXTENDS SOUTH ALONG THE FRONT RANGE IN COLORADO AND BACK TO THE EAST AS A WARM FRONT OVER THE SOUTHERN HALF OF OUR CWA. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS HAVE DEVELOPED EARLY THIS MORNING ACROSS OUR CWA AS A WARM FRONT HAS LIFTED NORTH WITH GOOD MOISTURE AND MARGINAL INSTABILITY IN PLACE...AND SUPPORT FROM LLJ/MID LEVEL THETA-E CONVERGENCE. SHORT RANGE GUIDANCE HAS DECENT HANDLE ON SHOWERS/THUNDERSTORMS IN EASTERN COLORADO...HOWEVER IS NOT DOING A GOOD JOB WITH ACTIVITY ALONG FRONT ACROSS REST OF CWA. WHILE CHANCE OF MEASURABLE IS NOT AS GREAT...COVERAGE ON RADAR HAS INCREASED QUITE A BIT OVER THE LAST FEW HOURS...SO I WENT AHEAD AND INCREASE POPS TO CHANCE CATEGORY. IVE TRENDED THIS ACTIVITY NORTHWARD THROUGH SUNRISE BASED ON TIMING OF FRONT. I COULD NT RULE OUT ACTIVITY POSSIBLY LINGERING THROUGH MID MORNING...HOWEVER IT APPEARS BEST ISENTROPIC SUPPORT AND FORCING WILL BE NORTH OF OUR CWA BY THAT POINT. WILL NEED TO MONITOR SHORT TERM TRENDS. OTHER IMMEDIATE CONCERN IS POSSIBILITY OF FOG DEVELOPMENT. THERE HAS BE LIGHT FOG REPORTED OVER PARTS OF SW NEBRASKA...AND WITH VERY GOOD BL MOISTURE I COULD NT RULE OUT ADDITIONAL FOG DEVELOPMENT FURTHER SOUTH. THE INHIBITING FACTOR WILL BE INSULATION FROM CLOUD COVER AND LESS FAVORABLE BL CONDITIONS BEHIND LIFTING WARM FRONT. HAVE KEPT PATCHY FOG MENTION ACROSS NORTHERN PART OF CWA THIS MORNING. AFTER PRECIP ENDS THIS MORNING FORECAST SHOULD REMAIN DRY THROUGH SUNDAY WITH H5 RIDGE STRENGTHENING...LARGE SCALE SUBSIDENCE OVER OUR CWA...AND MEAN STORM TRACK SHIFTING NORTH. LEE TROUGH WILL STRENGTHEN BY THIS WEEKEND WITH HOT AND BREEZY CONDITIONS EACH AFTERNOON. VERY LITTLE DIFFERENCE REGARDING AIR MASS OVER OUR CWA...WITH H85 TEMPS IN THE 28-31C RANGE SUPPORTING HIGHS IN THE UPPER 90S/NEAR 100F. SAW LITTLE REASON TO DEVIATE FROM PREVIOUS FORECAST WHICH HAD GOOD HANDLE ON MODEL TRENDS. DEPENDING ON AFTERNOON MIXING WE COULD SEE RH VALUES APPROACH RED FLAG CRITERIA IN THE WEST SAT/SUN. AT THIS POINT IT DOES NT APPEAR THAT WE WILL SEE THE WIND/RH CROSSOVER NECESSARY FOR HIGHLIGHTS...BUT WE WILL NEED TO MONITOR. .LONG TERM...(MONDAY THROUGH THURSDAY) ISSUED AT 251 AM MDT FRI AUG 23 2013 WHILE THE PAST FEW EXTENDED RANGE FORECASTS HAVE SOUNDED LIKE A BROKEN RECORD - HOT AND DRY - IT APPEARS AN END IS IN SIGHT. EARLY NEXT WEEK AN UPPER LEVEL RIDGE WILL BE CENTERED OVER KANSAS...WITH A A NORTH-SOUTH ORIENTED SURFACE TROUGH DEVELOP ALONG EASTERN COLORADO. THE ECMWF HAD PREVIOUSLY BEEN A BIT MORE CONSERVATIVE WITH TEMPS BUT NOW HAS COME AROUND TO BETTER MATCH THE GFS AND GEM WITH TEMPS IN THE LOW 30S C...TRANSLATING TO MID TO UPPER 90S IN THE FIRST HALF OF THE WEEK. TRIPLE-DIGIT TEMPS LOOK ALMOST LIKELY ON MONDAY AND TUESDAY FOR THE NORMAL HOT SPOTS...PLACES LIKE TRIBUNE...HILL CITY...AND MCCOOK...APPROACHING /BUT PROBABLY NOT EXCEEDING/ RECORDS IN SOME SPOTS. LATER IN THE WEEK THE RIDGE WILL SLOWLY NUDGE FARTHER EAST BRINGING RELIEF TO THE HEAT...SOMETHING THE OPERATIONAL GFS IS A BIT SLOW TO REALIZE BUT THE GEFS MEAN AND ECMWF HAVE BEEN CONSISTENT WITH THE PAST FEW RUNS. PRECIP CHANCES ARE NEAR NIL WITH THE RIDGE OVER US...BUT AS IT MOVES EAST WE COULD SEE CHANCES INCREASE TOWARDS THE WEEKEND. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 529 AM MDT FRI AUG 23 2013 SHOWERS/THUNDERSTORMS WILL LINGER WITHIN VICINITY OF KMCK TERMINAL THROUGH MID MORNING BEFORE ACTIVITY DISSIPATES OR SHIFTS NORTH/EAST. CANT COMPLETELY RULE OUT ADDITIONAL ACTIVITY REDEVELOPING LATER TODAY WITH SMALL SCALE LOW IN EASTERN COLORADO...HOWEVER WILL HOLD THIS OUT OF TAFS FOR NOW. OTHER AVIATION CONCERN THIS MORNING WITH BE PATCHY FOG. MVFR CIGS HAVE BEEN REPORTED AT TIMES AT KMCK...THOUGH WITH PRECIP IN VICINITY AND WINDS SHIFTING TO THE SOUTH I DONT THINK THIS WILL PREVAIL. KGLD SHOULD REMAIN WITHIN VFR...THOUGH WITH BETTER CHANCE TO SEE CLEARING SKIES AROUND SUNRISE I DONT WANT TO COMPLETELY RULE OUT MVFR VIS DEVELOPING FOR A SHORT PERIOD THIS MORNING. WILL LEAVE TEMPO IN PLACE AT KMCK FOR NOW...AND KEEP KGLD AT 6SM. BEYOND THIS MORNING VFR CONDITIONS SHOULD PREVAIL. LIGHTS WINDS WILL BEGIN TO INCREASE OUT OF THE THE SOUTH THIS AFTERNOON WITH LEE TROUGH DEVELOPMENT...WITH SUSTAINED WINDS GENERALLY AROUND 13-15KT...AND OCCASIONAL GUSTS. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...DR SHORT TERM...DR LONG TERM...JJM AVIATION...DR
AREA FORECAST DISCUSSION
NWS TOPEKA KS
623 AM CDT Fri Aug 23 2013 .SHORT TERM...(Today and Tonight) Issued at 335 AM CDT FRI AUG 23 2013 A broad upper level ridge of high pressure will be centered over the state of Kansas for the next 24 hours. early this morning, elevated showers were developing due to weak isentropic lift north of an old outflow boundary across west central KS. At this time I think the showers should remain just west of the cwa...though some isolated showers may develop near sunrise across the southwest and northern counties of the CWA, but should dissipate by mid morning. May place a 10 to 14 pop across the southwest and northern counties in case any isolated showers develop. Widespread convection along the foothills of CO will cause periods of high clouds to move across the CWA Today. The 06Z NAM is the only numerical model that breaks out deep moist convection across north central KS late this afternoon and into the early evening hours. The NAM may be trying to bring the MCV from the CO foothill convective complex too far south across the center of the H5 ridge axis. The GFS, arw, nmm and RAP show the the mcv rotating farther northeast across western and central NE and show no qpf developing across north central KS this afternoon. Just in case the NAM solution may be accurate I inserted 10 to 14 pops for late this afternoon and early evening across the northwest counties of the CWA. High temperatures Today may be dependent on the amount of high clouds. if the high clouds thin out this afternoon then highs will reach into the lower to mid 90s. If we keep a thicker veil of high clouds through the afternoon hours, then highs may only reach the upper 80s to around 90. Tonight, if any showers or isolated thunderstorms develop across north central KS they should dissipate after sunset. skies should become mostly clear through the night. overnight lows will drop into the upper 60s to lower 70s. .LONG TERM...(Saturday through Thursday) Issued at 335 AM CDT FRI AUG 23 2013 Medium range models are very similar in building upper ridge eastward through the weekend with axis over MO before retrogressing slightly and amplifying across KS through most of next week. This will allow for only weak inhibition by peak heating over the weekend...but a strengthening cap into next week. However with the exception of diurnal heating...no significant forcing evident to warrant any pops at this point...and even less confidence into next week. Therefore will keep the fcst through the extended dry. The llvl thermal fields only warm slightly from the weekend into the middle of next week...so the current fcst of only minor high temp increases thru the middle 90s into next week looks good for now. There is some concern that soil conditions steadily drying out and some hint of more veering llvl windfields by the middle of next week could lead to higher temps in the western cwa. A slight increase in dewpoints into next week with the slightly warmer temps should inch heat indices to around the century mark for most areas through next week. && .AVIATION...(For the 12Z TAFs through 12Z Saturday Morning) Issued at 619 AM CDT FRI AUG 23 2013 Expect VFR conditions for the next 24 hours at the TAF sites. The mid level clouds should prevent widespread ground fog at both KMHK and KTOP this morning. FEW to SCT CU will develop this afternoon and should dissipate after sunset. FEW-SCT mid and high clouds Tonight. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Gargan LONG TERM...63 AVIATION...Gargan
AREA FORECAST DISCUSSION
NWS TOPEKA KS
340 AM CDT Fri Aug 23 2013 .SHORT TERM...(Today and Tonight) Issued at 335 AM CDT FRI AUG 23 2013 A broad upper level ridge of high pressure will be centered over the state of Kansas for the next 24 hours. early this morning, elevated showers were developing due to weak isentropic lift north of an old outflow boundary across west central KS. At this time I think the showers should remain just west of the cwa...though some isolated showers may develop near sunrise across the southwest and northern counties of the CWA, but should dissipate by mid morning. May place a 10 to 14 pop across the southwest and northern counties in case any isolated showers develop. Widespread convection along the foothills of CO will cause periods of high clouds to move across the CWA Today. The 06Z NAM is the only numerical model that breaks out deep moist convection across north central KS late this afternoon and into the early evening hours. The NAM may be trying to bring the MCV from the CO foothill convective complex too far south across the center of the H5 ridge axis. The GFS, arw, nmm and RAP show the the mcv rotating farther northeast across western and central NE and show no qpf developing across north central KS this afternoon. Just in case the NAM solution may be accurate I inserted 10 to 14 pops for late this afternoon and early evening across the northwest counties of the CWA. High temperatures Today may be dependent on the amount of high clouds. if the high clouds thin out this afternoon then highs will reach into the lower to mid 90s. If we keep a thicker veil of high clouds through the afternoon hours, then highs may only reach the upper 80s to around 90. Tonight, if any showers or isolated thunderstorms develop across north central KS they should dissipate after sunset. skies should become mostly clear through the night. overnight lows will drop into the upper 60s to lower 70s. .LONG TERM...(Saturday through Thursday) Issued at 335 AM CDT FRI AUG 23 2013 Medium range models are very similar in building upper ridge eastward through the weekend with axis over MO before retrogressing slightly and amplifying across KS through most of next week. This will allow for only weak inhibition by peak heating over the weekend...but a strengthening cap into next week. However with the exception of diurnal heating...no significant forcing evident to warrant any pops at this point...and even less confidence into next week. Therefore will keep the fcst through the extended dry. The llvl thermal fields only warm slightly from the weekend into the middle of next week...so the current fcst of only minor high temp increases thru the middle 90s into next week looks good for now. There is some concern that soil conditions steadily drying out and some hint of more veering llvl windfields by the middle of next week could lead to higher temps in the western cwa. A slight increase in dewpoints into next week with the slightly warmer temps should inch heat indices to around the century mark for most areas through next week. && .AVIATION...(For the 06Z TAFs through 06Z Friday Night) Issued at 1148 PM CDT THU AUG 22 2013 Light to calm winds and mostly clear skies may lead to some MVFR VSBYS at TOP and MHK from 10 to 13Z and have added a tempo group for now. Outside of any fog VFR conditions are expected. South southeast winds will increase to around 10 kts by 16Z, then decrease after 01Z Saturday. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Gargan LONG TERM...63 AVIATION...53
AREA FORECAST DISCUSSION
NWS JACKSON KY
147 AM EDT FRI AUG 23 2013 .UPDATE... ISSUED AT 1055 PM EDT THU AUG 22 2013 WENT AHEAD AND LOWERED POPS A BIT MORE THROUGH THE OVERNIGHT WITH CONVECTION DYING OFF. THE HRRR AND RAP13 MODELS STILL REGENERATE SOME ACTIVITY TOWARDS DAWN...AND WILL CONTINUE TO ROLL WITH AN UPTICK IN POPS FOR NOW. UPDATE ISSUED AT 836 PM EDT THU AUG 22 2013 CONVECTION SEEMS TO BE ON THE DECLINE BESIDES A MORE ORGANIZED LINE OF SHOWERS AND THUNDERSTORMS AFFECTING WEST VIRGINIA...AS WELL AS SOME SLIGHTLY BETTER CLUSTERED CONVECTION GENERATED FROM A PASSING OUTFLOW BOUNDARY OUT IN NORTH CENTRAL KENTUCKY. AS SUCH...HAVE LOWERED POPS FOR THE REST OF THIS EVENING. THE LAST FEW HRRR RUNS HAVE ALSO SHOWN A GENERAL DECLINE THROUGH THE EVENING. ONCE THE REMAINS OF THE FRONTAL BOUNDARY AND A PASSING SHORT WAVE TROUGH MOVE THROUGH CLOSER TO DAWN...SOME SLIGHTLY BETTER COVERAGE WILL BE POSSIBLE...MAINLY IN THE NORTHEAST. STILL...GIVEN THE CURRENT OVERALL DOWNWARD TREND...FELT IT WARRANTED TO TRIM BACK THE POPS A BIT INTO THE DAY ON FRIDAY AS WELL. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT) ISSUED AT 337 PM EDT THU AUG 22 2013 ISOLATED TO SCATTERED CONVECTION ACROSS THE AREA HAS REMAINED UNORGANIZED AND TAME SO FAR TODAY...WITH LITTLE UPPER LEVEL SUPPORT AVAILABLE. A SHORT WAVE ON WATER VAPOR IMAGERY OVER THE UPPER MS VALLEY IS MOVING ESE...WHILE AN OLD OUTFLOW BOUNDARY AT THE SURFACE IS FOCUSING CONVECTIVE DEVELOPMENT ACROSS CENTRAL OH AND INDIANA. AS THE SHORT WAVE MOVES INTO THE OH VALLEY TONIGHT...THERE WILL BE BETTER UPPER LEVEL SUPPORT FOR PRECIPITATION ACROSS THE FORECAST AREA. THE EXACT EVOLUTION OF CONVECTION DEVELOPING ACROSS OH AND INDIANA IS UNCERTAIN...AND THE 17Z HRRR HAS MOST PRECIPITATION DYING OUT BY 02Z. HOWEVER IT DOES SHOW REDEVELOPMENT AROUND 05Z MOST LIKELY IN ASSOCIATION WITH AN UPPER LEVEL SPEED MAX ASSOCIATED WITH THE UPPER TROF. THE NAM IS MOST SUPPORTIVE OF PRECIPITATION OVERNIGHT...BUT THE GFS...ECMWF AND GEM ALL POINT TOWARDS A CHANCE OF SHOWERS AND THUNDERSTORMS. IT DOES APPEAR THE BEST SUPPORT WILL BE OVER THE NORTHERN AND EASTERN PORTION OF THE FORECAST AREA AND HAVE ELECTED TO GO WITH LIKELY PROBABILITY OF RAIN CHANCES IN THESE AREAS WITH A CHANCE IN THE SOUTHWEST. WEAK COLD FRONT WILL NOT CLEAR THE AREA UNTIL FRIDAY EVENING...SO WILL CONTINUE WITH A CHANCE OF SHOWERS AND THUNDERSTORMS FRIDAY...BUT DECREASE CHANCES FROM THE NORTH DURING THE DAY. WITH PRECIPITABLE WATER AROUND 1.9 INCHES OR NEAR THE 90TH PERCENTILE...WILL CONTINUE TO MENTION HEAVY RAIN AND FLASH FLOOD POSSIBILITY IN THE HAZARDOUS WEATHER OUTLOOK FOR TONIGHT. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 337 PM EDT THU AUG 22 2013 OT A LOT OF CHANGE FROM PREVIOUS FORECAST. MODELS ARE STILL IN RELATIVELY GOOD AGREEMENT THAT THE UPPER AIR PATTERN WILL CONSIST OF A LARGE 500MB RIDGE ACROSS THE SOUTH CENTRAL CONUS...EXPECTED TO REMAIN IN PLACE THROUGH THE DURATION OF THE FORECAST PERIOD. WITH UPPER LEVEL TROUGHING OFF BOTH THE NW AND NE COAST...EASTERN KY WILL FIND ITSELF WITHIN THE RIDGING PATTERN...BUT ON THE WINDWARD SIDE OF THE NE TROUGHING PATTERN. ANY SHORTWAVE THAT TRAVELS ALONG THE TROUGH AXIS WILL MAKE ITS WAY NEAR EASTERN KY DESPITE THE STRONG RIDGING IN PLACE. HOWEVER...WITH SOMEWHAT LESS AGREEMENT ON THE SMALLER SCALE...ANY SHORTWAVES AND RESULTING RAIN CHANCES WILL BE BEST LEFT TO A MODEL CONSENSUS. WITH A GOOD VEERING WIND PROFILE...AND TEMPERATURES EXPECTED TO BE WARMER AND MORE HUMID THAN HAVE BEEN OVER THE PAST FEW WEEKS...ALL MODELS ARE POINTING AT THE POTENTIAL FOR AFTERNOON INSTABILITY AND CONVECTION ACROSS THE EASTERN PORTION OF THE STATE THROUGH THE ENTIRE FORECAST PERIOD. THE ONLY CAVEAT TO THIS IS THE FACT THAT GFS40 SOUNDINGS /BOTH CURRENT AND PREVIOUS/ ARE SHOWING AN ABUNDANT AMOUNT OF DRY AIR AT ALL LEVELS...WITH ONLY THE POTENTIAL FOR A SCT THIN LAYER OF DIURNAL CLOUDS. AND THOUGH THERE IS A GOOD VEERING PATTERN MENTIONED ABOVE...MOST OF THIS TAKES PLACE IN THE MID LEVELS RATHER THAN THE LOWER LEVELS...WITH A LOW AMOUNT OF CAPE AND A VERY LIMITED AMOUNT OF TIME IN THE AFTERNOON WHERE THERE IS NOT A CAPPING INVERSION. ALL THINGS CONSIDERED...DID PUT IN SOME SLIGHT CHANCE POPS IN THE AFTERNOON TO GO ALONG WITH MODEL CONSENSUS...BUT EXPECT THUNDERSTORM DEVELOPMENT TO BE EVEN MORE ISOLATED IN COMPARISON TO SHOWER POTENTIAL. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 146 AM EDT FRI AUG 23 2013 FOG WILL CONTINUE TO DEVELOP TONIGHT...THICKENING IN THE DEEPER VALLEYS AND SPREADING OUT FROM THERE. NOT CONFIDENT IN EVENTUAL OUTCOMES AT TAF SITES...BUT AT LEAST MVFR CAN BE EXPECTED AT TIMES... AND POSSIBLY IFR. ISOLATED SHOWERS COULD ALSO REDEVELOP TOWARD DAWN...ESPECIALLY IN THE NE PART OF THE AREA. FOG WILL THEN DISSIPATE WELL AFTER SUNRISE...POSSIBLY BRIEFLY LIFTING INTO AN IFR OR LOW MVFR CLOUD DECK BEFORE RISING FURTHER AND SCATTERING LATER IN THE MORNING. WITH DAYTIME HEATING...SCATTERED THUNDERSTORMS MAY BE A THREAT DURING THE MID-LATE AFTERNOON HOURS. OUTSIDE OF PRECIP IN THE AFTERNOON AND EVENING...VFR IS EXPECTED. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GEOGERIAN SHORT TERM...SBH LONG TERM...JMW AVIATION...HAL
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
741 PM EDT SAT AUG 24 2013 .SYNOPSIS... HIGH PRESSURE AND PLEASANT WEATHER WILL CONTINUE THROUGH THE WEEKEND. AN UPPER-LEVEL DISTURBANCE WILL APPROACH EARLY NEXT WEEK AND WILL GIVE US THE CHANCE OF SHOWERS AND STORMS. TEMPERATURES WILL CLIMB ABOVE NORMAL BY THE END OF THE WORK WEEK. && .NEAR TERM /THROUGH SUNDAY/... 600 PM UPDATE... DEW POINTS CONTINUE TO SLOWLY DROP. NUDGED MIN TEMPS DOWN ACROSS NORTH WITH LOWER TD/S. BROUGHT IN A LITTLE MORE CLOUDS (CIRRUS) TOWARD MORNING. HRRR SUGGESTING SOME BLOW OFF DEBRIS FROM SYSTEM JUST NORTH OF GREAT LAKES. KEPT A FEW MORE CLOUDS RIDGES APPALACHIAN PLATEAU COUNTIES. WITH EAST TO NORTHEAST FLOW COULD CONTINUE A FEW UP-SLOPE CLOUDS. PREVIOUS DISCUSSION FOLLOWS... DRY ADIABATIC CONDITIONS FROM CCL TO SFC HAVE DEVELOPED A SCT CU FIELD ACROSS THE HIGHER TERRAIN AND POINTS S OF I-70. THIS FIELD WILL CONTINUE TO GROW THIS AFTN AS TEMPS CLIMB INTO THE M-U 70S. DAYTIME DRIVEN CU WILL WANE WITH SUNSET...LEAVING A CLR- MCLR SKY. CROSSOVER TEMPS OF M-U 50S WOULD NOT YIELD FOG FORMATION OVERNIGHT EVEN IN THE DEEPER HOLLOWS OF THE NRN WV MTNS. H5 HEIGHTS BUILD SUN AS ANTICYCLONE OVER THE MIDWEST SHIFTS A LITTLE E. BUFR SOUNDINGS ILLUSTRATE AN INC IN MID AND HIGH CLOUDS DURING THE AFTN HRS FROM THE NW AS MSTR SPILLS OVER TOP THE NRN PERIPHERY OF THE RIDGE. ANOTHER FACTOR FOR INC HIGH CLOUDS IS UPR LVL DIV DEPICTED BY NCEP MDLS THE SECOND HALF OF SUN. CU TRIGGER TEMPS WILL BE IN THE UPR 70S AGAIN TMRW AND WE WILL SURPASS THOSE NUMBERS BY LUNCH TIME...SO ANOTHER CU FIELD CAN BE ANTICIPATED. TWEAKED INHERITED SKY GRIDS HOWEVER FOR A LARGE PART MID AND HIGH CLOUDS WILL BE NON - OPAQUED SO ROLLING WITH ANOTHER MSNNY FCST. NAM12BC GRIDS USED FOR MAXT SUN...WHILE MOSGUIDE BC USED FOR MINT && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/... BENIGN WEATHER PERSISTS THROUGH MONDAY WITH MID-LVL HIGH PRESSURE STILL IN CONTROL OF OUR WEATHER DESPITE ITS WESTWARD PROGRESSION. BELT OF STRONGER H7-H5 WINDS MAKES STEERING FLOW NW...ALLOWING A BAROCLINIC ZONE TO DROP THROUGH THE EMPIRE STATE INTO NRN PA BY MON EVE. STILL THINK AMOUNT OF DRY AIR INDICATED BUT -1 STD PWATS WILL ALLOW FOR ANOTHER PCPN FREE MONDAY...HWVR AMOUNT OF INCOMING SOLAR RADIATION WILL BE DIMINISHED THROUGH THE DAY ESPECIALLY ACROSS I-80 CORRIDOR. H8 TEMPS UNDER LIGHT SW WINDS IN THE BL CLIMB TO 16C...WHICH WILL PUSH TEMPS INTO THE L-M 80S. THIS COULD BE THE WARMEST DAY TO DATE OF THE ENTIRE MONTH IF WE HIT 85F AT PIT...WHICH SOME STATISTICAL GUIDANCE SUGGESTS. H5 ANTICYCLONE WILL STRENGTHEN THRU WED...LEAVING FCST AREA IN NWLY FLOW ALOFT. SVRL SHRTWV TROFS WILL PROGRESS THRU THIS FLOW DURG THE MON NGT-WED TIMEFRAME AS DP MSTR RETURNS TO THE RGN. PRIMARY FACTOR INFLUENCING THE CVRG AND INTENSITY OF CNVCTN DURG THIS TIME WILL BE MID-LVL LAPSE RATES. DYNAMICALLY...PATTERN WILL BCM MORE FAVORABLE FOR SVR WX AS WIND FIELD STRENGTHENS. BOTH ECMWF AND GFS DEPICT CNVCTN ASSOCIATED WITH WAVES PASSING THRU MON EVE AND TUE AFTN-EVE. POPS WERE ADJUSTED APPROPRIATELY TO REFLECT THIS PSBLTY. ECMWF AND GFS DIFFER ON TIMING OF SHRTWV TROF ON WED. OWING TO UNCERTAINTIES IN TIMING...HAVE NOT INCRD POPS CONSIDERABLY ON WED OR MENTIONED SVR WX IN HWO. BUT THIS PSBLTY WILL NEED TO BE MONITORED CLOSELY. CONTD MAXIMA IN THE LOW-MID 80S XPCD THRU WED. MINIMA WILL INCR MARKEDLY MON NGT AND TUE OWING TO LOW-LVL MSTR ADVCTN...WITH LOWS IN THE MID-UPR 60S LKLY MANY AREAS TUE NGT. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... BY LATE IN THE LONG TERM...UPPER-LEVEL RIDGE WILL SHIFT BACK TO THE EAST AND SURFACE HIGH WILL TAKE OVER. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... VFR WITH LIGHT WINDS THROUGH THE PERIOD. .OUTLOOK.../SUNDAY NIGHT THROUGH THURSDAY/... A SERIES A SHORTWAVES MAY BRING RESTRICTIONS AT TIMES TUESDAY THROUGH THURSDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
328 PM CDT FRI AUG 23 2013 .SYNOPSIS... ISSUED AT 326 PM CDT FRI AUG 23 2013 RAP H5 ANALYSIS THIS AFTERNOON SHOWS HEIGHT RISES DOMINATING THE CENTRAL CONUS...AS THE UPPER HIGH THAT WILL BE BRINGING US THE HEAT WAVE COME SUNDAY IS STARTING TO STRENGTHEN OVER KANSAS...WITH THE RIDGE AXIS BUILDING NORTH INTO THE RED RIVER VALLEY. WATER VAPOR SHOWS A COUPLE OF WEAK WAVE ACROSS THE DAKOTAS THAT WILL BE ROUNDING THE TOP OF THE RIDGE TONIGHT. AT THE SFC...HIGH PRESSURE HAS NOW MOVED INTO THE GREAT LAKES...WITH RETURN FLOW BECOMING ESTABLISHED ACROSS THE AREA. FRONT THAT SETTLED ALONG THE IOWA BORDER THURSDAY HAS COMPLETELY WASHED OUT...WITH THE HIGH DEWPOINTS THAT HAD POOLED OVER IOWA LAST NIGHT NOW SURGING NORTH ON THE SOUTH WINDS...WITH CU FIELD MOVING NORTH OUT OF SRN MN ALSO DENOTING WHERE DEWPOINT GO FROM THE 50S BACK UP TO THE UPPER 60S TO AROUND 70. && .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 326 PM CDT FRI AUG 23 2013 MAIN CONCERN RIGHT OFF THE BAT WILL BE THE POTENTIAL FOR THUNDERSTORMS WITHIN THE NEXT COUPLE OF HOURS OVER SW MN. 19Z SPC MESOANALYSIS SHOWS A BUBBLE OF 3000-4000 J/KG OF MLCAPE HAS DEVELOPED IN THE MN/SD/NEB/IA BORDERS REGION. IN ADDITION...LLJ AND ASSOCIATED MOISTURE TRANSPORT IS BEGINNING TO INCREASE ACROSS NE NEB AND SE SODAK. IN THIS REGION...THE HRRR ALONG WITH ALL MEMBERS OF THE 15Z HOPWRF SHOW AN AREA OF SCT TSTMS DEVELOPING AROUND SIOUX FALLS...THEN DRIFTING NNE TOWARD THE UPPER MN RIVER VALLEY. HAVE SOME ISO THUNDER WORDING OUT THERE BETWEEN 22 AND 02Z AS A RESULT. INTERESTINGLY...BOTH THE HRRR AND HOPWRF SHOW THIS ACTIVITY BEING DIURNALLY DRIVEN...WITH IT MOSTLY DISSIPATED BY 03Z. FOR TONIGHT...STILL LOTS OF UNCERTAINTY AS TO HOW THINGS WILL UNFOLD FOR PRECIP AS WE GET INTO A WAA REGIME...BUT IT IS STARTING TO LOOK UNLIKELY THAT MUCH IS SEEN. LOOKING AT TEMP/MOISTURE ADVECTION AROUND THE H7 LEVEL...THE GFS/NAM SHOW TWO AREAS OF ENHANCED FORCING IN THE REGION TONIGHT...ONE DOWN ACROSS IOWA AND THE OTHER UP ACROSS NRN MN. THE 23.12 ECMWF ONLY HAS THE NRN FORCING SOURCE. GIVEN THAT THE NOSE OF THE LLJ LOOKS TO BE DIRECTED INTO NRN MN...CONFIDENCE IS HIGHEST IN SOMETHING TRACKING ACROSS NRN MN /PER THE NMM AND SPCWRF REFLECTIVITY FORECASTS/. HOWEVER...GIVEN THE BROAD ZONE OF WAA/MOISTURE TRANSPORT MOVING ACROSS THE AREA CAN NOT RULE OUT GETTING SOME AT LEAST SCT SHRA/TSRA AS THE LLJ WORKS ACROSS THE AREA OVERNIGHT INTO SATURDAY MORNING. FOR THE POP GRIDS...DID NUDGE THEM DOWN SOME...AND ALSO SLOWED DOWN THE ERN PROGRESSION OF THINGS...CLOSER TO A NAM TIMING. DURING THE DAY ON SATURDAY...A STRONG CAPPING INVERSION WILL BE MOVING IN...WHICH SHOULD SHUT DOWN THE PRECIP FOR MOST OF MN BY THE AFTERNOON...WITH CHANCES LINGERING ACROSS WRN WI. LAST QUESTION MARK FOR THIS FORECAST IS HOW WARM DO WE GET ON SATURDAY. THIS WILL DEPEND HIGHLY ON HOW QUICKLY SKIES CAN CLEAR OUT FROM WEST TO EAST FROM THE MORNING INTO THE AFTERNOON. ERN MN/WRN WI WILL LIKELY ENJOY THE CLOUD COVER FOR A GOOD CHUNK OF THE DAY...WHICH SHOULD HELP HOLD HIGHS BACK INTO LOW/MID 80S...THOUGH WITH DEWPS UP AROUND 70...IT WON`T EXACTLY FEEL COMFORTABLE. OUT IN WRN MN...CLOUDS SHOULD CLEAR OUT EARLY ENOUGH TO ALLOW THE RETURN OF 90S...THOUGH DEPENDING ON HOW QUICKLY THE SUN ARRIVES...THE WEST COULD SEE HIGHS ANYWHERE FROM THE UPPER 80S /MORE CLOUDS/ TO THE UPPER 90S /VERY LITTLE CLOUD COVER/. .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 326 PM CDT FRI AUG 23 2013 MAIN CONCERN IN THE EXTENDED IS WELL ADVERTISED HEAT WAVE THAT IS FORECAST TO BRING NEAR RECORD TEMPERATURES BEGINNING SUNDAY...AND LASTING THROUGH AT LEAST THE MIDDLE OF THIS WEEK. THE LONG DURATION OF THIS HEAT...WITH THE WARM OVERNIGHT MIN TEMPS IS THE REASON BEHIND THE EXCESSIVE HEAT WATCH THAT WAS ISSUED EARLIER THIS MORNING. MASS TEMPERATURE FIELDS FROM THE H925/H850 LAYER...TOGETHER WITH THE 500MB HEIGHTS SUPPORT THIS HEAT WATCH...BUT IF ANY DEBRIS CLOUDS FROM AN OVERNIGHT MCS SPREAD ACROSS THE REGION...OR IF THE MCS ITSELF BUILDS TO THE SOUTH AS INDICATED BY THE GFS AND ECMWF 23.12...THEN FORECAST MAX TEMPERATURES WILL BE OVERDONE BY SEVERAL DEGREES. AT THE START OF THE PERIOD LOW LEVEL WARM AIR ADVECTION WITH SOUTHWEST FLOW WILL BE WELL ESTABLISHED ACROSS THE CWA...SO HAVE RAISED MIN TEMPERATURES SATURDAY NIGHT/SUNDAY MORNING. ALSO HAVE INCREASED THE WINDS HIGHER THAN GUIDANCE AS WELL...ESPECIALLY ALONG THE UPPER MINNESOTA RIVER VALLEY WHERE THE DOWNSLOPE COMPONENT OFF THE BUFFALO RIDGE WILL ADD A FEW EXTRA KNOTS. THESE WARMER LOW TEMPERATURES WILL TRANSLATE INTO AFTERNOON HIGHS IN THE MID TO UPPER 90S ON SUNDAY AS THE BOUNDARY LAYER MIXES UP TO 850MB AS SHOWN VIA THE BUFR SOUNDINGS. ANOTHER RESULT OF THIS DEEP MIXING WILL BE DEWPOINT DROPPING INTO THE MID 60S DURING THE AFTERNOON. IF THE NAM 23.12 VERIFIES...DEWPOINTS COULD FALL INTO THE UPPER 50S AT A FEW LOCATIONS. USED THE MIXDOWN TOOL TOGETHER WITH BIAS CORRECTED MODEL BLEND TO POPULATE BOTH T AND TD ON SUNDAY. LOOKING AHEAD...INCREASED LOW LEVEL MOISTURE WILL BRING HIGHER TDS ON MONDAY WITH AFTERNOON MAX TEMPS ONCE AGAIN IN THE MID TO UPPER 90S. THIS WILL BE THE TREND THROUGH THE EXTENDED...WITH THE ONCE CAVEAT BEING THE CONVECTIVE POTENTIAL. AS ALLUDED TO EARLIER...OVERNIGHT CONVECTION WILL DEVELOP AS SHORTWAVES PERIODICALLY ROUND THE BASE OF THE UPPER LEVEL RIDGE ACROSS THE INTERNATIONAL BORDER. THE 23.12Z GFS AND ECMWF DEVELOP CONVECTION ACROSS THE ARROWHEAD SATURDAY NIGHT...AND OVER LAKE SUPERIOR SUNDAY NIGHT...WITH THE SECOND FEATURE BUILDING SOUTHWEST AS IT IS FED BY THE LOW LEVEL JET. A SHORTWAVE THAT IS CURRENTLY LOCATED OFF THE BAJA PENINSULA IS FORECAST TO MOVE ACROSS THE UPPER MIDWEST MONDAY NIGHT...AND PUSH A FRONTAL BOUNDARY THROUGH CENTRAL MN AND NORTHERN WI. THIS ALSO COULD GIVE SOME REPRIEVE FROM THE HEAT BY MID WEEK...BUT CONFIDENCE IN THE SOUTHERN EXTEND OF THIS FRONTAL BOUNDARY IS LOW AT THIS TIME. THEREFORE FEEL THE POTENTIAL FOR DANGEROUS HEAT WAVE MERITS THE EXCESSIVE HEAT WATCH IN CENTRAL MN AND FAR WESTERN WI. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 1238 PM CDT FRI AUG 23 2013 MOISTURE BEGINNING TO SURGE NORTH IN ERNEST...AS EVIDENCED BY CU FIELD MOVING OUT OF SRN MN. MODEST INSTABILITY HAS DEVELOPED WITHIN THIS MOIST PLUME OVER SRN MN...WITH THE HRRR CONTINUING TO GENERATE AN AREA OF SCT TSTMS OVER SW MN THIS AFTERNOON. AS A RESULT...INCLUDED A VCTS FOR RWF BETWEEN 22Z AND 01Z. STILL NOT MUCH CONFIDENCE WITH HOW THINGS WILL UNFOLD TONIGHT INTO SATURDAY MORNING WITH RESPECT TO TSTM CHANCES. BOTH THE NAM/GFS WARM AIR AND MOISTURE ADVECTION AROUND 700 MB INDICATES A COUPLE OF AREAS OF ENHANCED FORCING FOR TSTMS TONIGHT...ONE DOWN INTO IA AND THE UP IN NRN MN...NICELY SPLITTING THE MPX AREA. BIG REASON FOR NOTHING MORE THAN A VCSH MENTION STILL IS THAT BY THE END OF THE HOPWRF AND HRRR /06Z TONIGHT/...NEITHER MODEL SHOWS ANYTHING DEVELOPING NEAR MN/WI AT THAT POINT...VERY POSSIBLE THAT THIS BIT OF WARM ADVECTION DOES NOT DO MUCH MORE THAN BRING IN A FIELD OF ACCUS. CONFIDENCE IS BETTER WITH WINDS. LOW LEVEL WINDS ARE FORECAST TO INCREASE DRAMATICALLY TONIGHT...AND ONCE MIXING PICKS UP ON SATURDAY...SHOULD HAVE TO PROBLEM MIXING DOWN BETTER THAN 20 KT GUSTS...WITH GUSTS OVER 30KTS NOT OUT OF THE QUESTION FOR WRN MN BY THE AFTERNOON. KMSP...LOW CONFIDENCE IN PRECIP POTENTIAL TONIGHT. AT THE VERY LEAST...FAVORED THE LATER TIMING DEPICTED BY THE NAM. FOR WINDS SATURDAY AFTERNOON...MIX DOWN TOOL ON THE NAM INDICATING GUSTS OVER 30 KTS POSSIBLE DURING THE AFTERNOON...BUT THAT WILL BE DEPENDENT IF WE CAN BREAK OUT INTO SOME SUNSHINE. /OUTLOOK FOR KMSP/ SUN...VFR. SW WIND 10-15 G25 KT. MON...VFR. SW WIND 10 KT. TUE...VFR. SW WIND 5 KT. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...EXCESSIVE HEAT WATCH FROM SUNDAY AFTERNOON THROUGH WEDNESDAY EVENING FOR MNZ047>051-054>070-073>078-082>085-091>093. WI...EXCESSIVE HEAT WATCH FROM SUNDAY AFTERNOON THROUGH WEDNESDAY EVENING FOR WIZ023-024. && $$ SYNOPSIS...MPG SHORT TERM...MPG LONG TERM...JRB AVIATION...MPG
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
105 PM CDT FRI AUG 23 2013 .UPDATE... 18Z AVIATION DISCUSSION ADDED BELOW. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 231 AM CDT FRI AUG 23 2013 MOISTURE GRADIENT INDICATED EARLY THIS MORNING ACROSS IA...INTO SD/FAR SW MN WHERE DEW PTS REMAIN IN THE 60S. THIS GRADIENT IS MOST LIKELY THE REMNANTS OF THE OLD FRONTAL BOUNDARY THAT MOVED INTO IA ON THURSDAY. IN ADDITION...DENSE FOG FORMED IN AREAS THAT RECEIVED LOTS OF RAINFALL IN NE IA/SW WI. THIS AREA WILL LIKELY MIX OUT AND DEEPEN THE MOISTURE ACROSS FAR SW/SC MN DURING THE DAY AS WINDS SHIFT TO THE S/SE. DUE TO THIS MOISTURE GRADIENT AND THE FACT THAT WINDS BEGIN TO INCREASE AND POOL IN SW MN...ISOLATED TSRA WILL BE POSSIBLE...ESPECIALLY IF A SFC BOUNDARY DEVELOPS WHICH IS LIKELY THE FORMATION OF THE WARM FRONT. SOME OF THE LOCAL MODELS /HOPWRF/ HAVE ISOLATED REFLECTIVITY RETURNS ALONG THIS MOISTURE GRADIENT THIS AFTN. THE BEST CHC/S OF RAINFALL WILL DEVELOP LATER TONIGHT AS THE LLJ BEGINS TO INCREASE ACROSS SD/IA/SW MN. THE PROXIMITY OF THIS LLJ...OR THE APEX OF THE JET WILL BE THE FOCUS OF TSRA DEVELOPMENT. THE LOCATION REMAINS IN QUESTION...BUT ENOUGH TRENDS IN THE SHORT TERM MODELS INDICATE SOMEWHERE IN EASTERN SD/WC OR SW MN. ANY DEVIATION TO THIS JET WILL LEAD TO THE DEVELOPMENT OF THE SHRA/TSRA FARTHER TO THE NORTH OR SOUTH. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 333 AM CDT FRI AUG 23 2013 ...SIGNIFICANT HEAT WAVE NEXT WEEK WITH RECORD-SETTING TEMPS POSSIBLE... THE FOCUS IN THE LONG TERM PORTION OF THE FORECAST CONTINUES TO BE ON HOT TEMPERATURES THROUGH MUCH OF THE UPCOMING WEEK. IN FACT...IT COULD BE THE LONGEST DURATION OF CONSECUTIVE DAYTIME HIGH TEMPERATURES IN THE MID 90S THAT MINNEAPOLIS HAS EXPERIENCED DURING THE LAST WEEK OF AUGUST SINCE 1948. PRIOR TO THE ARRIVAL OF THE HEAT...SATURDAY WILL FEATURE SCATTERED SHOWERS AND THUNDERSTORMS LIFTING NORTHEAST ACROSS THE AREA DURING THE MORNING...WITH AFTERNOON/EVENING CONVECTION PRIMARILY CONFINED TO WEST CENTRAL WI ALONG/NORTH OF THE WARM FRONT. BY SUNDAY...THE ENTIRE FORECAST AREA IS IN THE WARM SECTOR AHEAD OF THE EASTERN DAKOTAS TROUGH. 925-850MB TEMPERATURES CLIMB TO AROUND +27C TO +30C. WITH DEEP MIXING PROGGED TO ENSUE WITH BREEZY SOUTH/SOUTHWEST WINDS...EXPECT LOW/MID 90S TO BE EASILY ACHIEVED. SAID TEMPERATURES COMBINED WITH ANTICIPATED DEWPOINTS AROUND 70 DEGREES WOULD YIELD MAX HEAT INDEX VALUES OF 95-100 DEGREES...POSSIBLY EVEN A TAD HIGHER. ALTHOUGH THE DAYTIME PRECIPITATION CHANCES WILL BE DISPLACED TO THE NORTH OF THE FORECAST AREA...COULD SEE WIDELY SCATTERED ACTIVITY IN CENTRAL MN/WI ON SUNDAY NIGHT INTO MONDAY AS THE TROUGH SAGS INTO THE AREA. THE THERMAL RIDGE HOLDS FIRMLY IN PLACE ACROSS THE FORECAST AREA FROM MONDAY THROUGH THURSDAY PER THE GFS...WHICH WOULD MEAN CONTINUANCE OF HIGHS IN THE MID 90S. HOWEVER...THE 00Z ECMWF DIFFERED NOTABLY...IN THAT IT REDUCED HEIGHTS/TEMPS FOR WEDNESDAY AND THURSDAY /YIELDING HIGHS IN THE 80S/. THEREFORE HAVE A TINGE OF LOWERED CONFIDENCE THAT WE/D MEET HEAT ADVISORY CRITERIA FOR THE 4+ CONSECUTIVE DAYS NEEDED TO WARRANT AN EXCESSIVE HEAT WATCH/WARNING. WILL CONTINUE TO HIGHLIGHT THE EXCESSIVE HEAT THREAT IN THE HWO...AND SEE IF THE 12Z ECMWF TREND CONTINUES. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 1238 PM CDT FRI AUG 23 2013 MOISTURE BEGINNING TO SURGE NORTH IN ERNEST...AS EVIDENCED BY CU FIELD MOVING OUT OF SRN MN. MODEST INSTABILITY HAS DEVELOPED WITHIN THIS MOIST PLUME OVER SRN MN...WITH THE HRRR CONTINUING TO GENERATE AN AREA OF SCT TSTMS OVER SW MN THIS AFTERNOON. AS A RESULT...INCLUDED A VCTS FOR RWF BETWEEN 22Z AND 01Z. STILL NOT MUCH CONFIDENCE WITH HOW THINGS WILL UNFOLD TONIGHT INTO SATURDAY MORNING WITH RESPECT TO TSTM CHANCES. BOTH THE NAM/GFS WARM AIR AND MOISTURE ADVECTION AROUND 700 MB INDICATES A COUPLE OF AREAS OF ENHANCED FORCING FOR TSTMS TONIGHT...ONE DOWN INTO IA AND THE UP IN NRN MN...NICELY SPLITTING THE MPX AREA. BIG REASON FOR NOTHING MORE THAN A VCSH MENTION STILL IS THAT BY THE END OF THE HOPWRF AND HRRR /06Z TONIGHT/...NEITHER MODEL SHOWS ANYTHING DEVELOPING NEAR MN/WI AT THAT POINT...VERY POSSIBLE THAT THIS BIT OF WARM ADVECTION DOES NOT DO MUCH MORE THAN BRING IN A FIELD OF ACCUS. CONFIDENCE IS BETTER WITH WINDS. LOW LEVEL WINDS ARE FORECAST TO INCREASE DRAMATICALLY TONIGHT...AND ONCE MIXING PICKS UP ON SATURDAY...SHOULD HAVE TO PROBLEM MIXING DOWN BETTER THAN 20 KT GUSTS...WITH GUSTS OVER 30KTS NOT OUT OF THE QUESTION FOR WRN MN BY THE AFTERNOON. KMSP...LOW CONFIDENCE IN PRECIP POTENTIAL TONIGHT. AT THE VERY LEAST...FAVORED THE LATER TIMING DEPICTED BY THE NAM. FOR WINDS SATURDAY AFTERNOON...MIX DOWN TOOL ON THE NAM INDICATING GUSTS OVER 30 KTS POSSIBLE DURING THE AFTERNOON...BUT THAT WILL BE DEPENDENT IF WE CAN BREAK OUT INTO SOME SUNSHINE. /OUTLOOK FOR KMSP/ SUN...VFR. SW WIND 10-15 G25 KT. MON...VFR. SW WIND 10 KT. TUE...VFR. SW WIND 5 KT. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...EXCESSIVE HEAT WATCH FROM SUNDAY AFTERNOON THROUGH WEDNESDAY EVENING FOR MNZ047>051-054>070-073>078-082>085-091>093. WI...EXCESSIVE HEAT WATCH FROM SUNDAY AFTERNOON THROUGH WEDNESDAY EVENING FOR WIZ023-024. && $$ SHORT TERM...JLT LONG TERM...LS AVIATION...MPG
AREA FORECAST DISCUSSION
NWS GLASGOW MT
825 PM MDT SAT AUG 24 2013 .SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH MONDAY... EVENING UPDATE... CHANGE FOR THIS EVENING WAS TO REASSESS POPS AND SPREAD MENTIONABLE SLIGHT CHANCE ACROSS A LARGER SECTION OF THE CWA. CURRENTLY WITH THE STATIONARY BOUNDARY HOVERING OVER THE AREA... A FOCAL POINT WITH SOME VORTICITY HAS DEVELOPED FOR ANY MONSOONAL MOISTURE TO GENERATE RAIN SHOWERS OR A THUNDERSTORM OR TWO OVERNIGHT. A FEW SHOWERS ARE CROSSING THE MISSOURI RIVER FROM FERGUS TO PHILLIPS COUNTY AS OF 8PM ON RADAR AND HRRR MODEL DOES HAVE SOME WEAK NOCTURNAL DEVELOPMENT AS WELL. GAH PREVIOUS SHORT TERM DISCUSSION... A BROAD AREA OF HIGH PRESSURE OVER CENTRAL CONUS WILL MAINTAIN A PERSISTENT SOUTHWEST FLOW ALOFT OVER NORTHEAST MONTANA THROUGH THE SHORT TERM PERIOD. WITH 700MB TEMPERATURES STAYING ABOVE 10C AND THICKNESS HEIGHTS AROUND 580DM...SURFACE HIGHS WILL CONTINUE INTO THE 90S AND OVERNIGHT LOWS IN THE 60S. TONIGHT...A WEAK SHORTWAVE EMBEDDED IN THE FLOW ALOFT WILL UNDERCUT THE CWA WITH SOME ENERGY THAT WILL LIKELY PRODUCE STORMS TO OUR SOUTH AND EAST...AND POSSIBLY OUR SOUTHEAST CORNER. SUNDAY...SURFACE WINDS SHIFT TO THE SOUTHWEST AND THERMAL RIDGING WILL RAMP HIGHS UP INTO THE MID TO UPPER 90S FOR A HOT DAY. THERE IS SOME WEAK SURFACE BASED INSTABILITY AT 18Z THAT DISAPPEARS BY 00Z. SO WILL ONLY MAINTAIN SLIGHT CHANCE FOR ISOLATED THUNDER. SPC MAINTAINS MOST OF OUR CWA UNDER ITS CONVECTIVE OUTLOOK FOR GENERAL THUNDERSTORMS. SUNDAY NIGHT AND MONDAY...A SHORTWAVE DISTURBANCE MOVING THROUGH CENTRAL ALBERTA WILL NUDGE THE STATIONARY BOUNDARY SOUTHEAST A BIT WHICH WILL GIVE THE OVERRUNNING MOISTURE PLUME SOMETHING TO FOCUS ON. THE MOISTURE PLUME CONTINUES TO BE FROM AN AREA OFF THE COAST OF SOUTHERN AND BAJA CALIFORNIA. THEREFORE WITH THIS ADDITIONAL MOISTURE THERE IS AN INCREASED CHANCE FOR THUNDERSTORMS IN A BAND FROM SOUTHWEST MONTANA THROUGH CENTRAL MONTANA...POSSIBLY CLIPPING OUR WESTERN ZONES OVERNIGHT. THE BOUNDARY SAGS FROM THE NORTH ON MONDAY SO THE FAVORED AREA FOR STORMS WILL BE ALONG AND NORTH THE INTERNATIONAL BORDER. SOUTH OF THIS BOUNDARY THE HOT CONDITIONS OF SUNDAY WILL CONTINUE INTO MONDAY. HIGHS ARE EXPECTED WELL INTO THE MID TO UPPER 90S AGAIN. ANOTHER EMBEDDED SHORTWAVE AND ENHANCE VORTICITY WILL CREATE CONDITIONS FOR A CHANCE OF THUNDER ON MONDAY. SCT .LONG TERM...MONDAY NIGHT THROUGH SATURDAY... MADE SOME MINOR ADJUSTMENTS...ESPECIALLY WHERE BETTER MODEL AGREEMENT WAS EVIDENT FOR POPS...WX...ETC. THE WARM INFLUENCE OF THE WESTERN AND CENTRAL STATES RIDGE SEEMS TO BE IN PLACE OVER OUR CWA FOR THE DURATION OF THE EXTENDED FORECAST PERIOD. ALTHOUGH...JUST BEYOND THE FORECAST PERIOD...A STRONG COLD FRONT AND STORM SYSTEM SEEMS POISED TO PUSH THROUGH THE REGION FROM THE NORTHWEST. UNTIL THEN...EXPECT GENERAL SOUTHWESTERLY FLOW ALOFT WITH OCCASIONAL EMBEDDED SHORT WAVE DISTURBANCES. AT THIS TIME...MODELS ARE INDICATING THAT THESE PERIODS OF BETTER CHANCES FOR SHOWERS AND THUNDERSTORMS WILL CENTER AROUND WEDNESDAY. THAT BEING SAID...THE CENTRAL PLAINS RIDGE OF HIGH PRESSURE WILL BE VERY LARGE AND INFLUENTIAL AND MAY KEEP ANY SHORT WAVE DISTURBANCE PUSHED JUST WEST AND AWAY FROM OUR CWA. BMICKELSON PREVIOUS LONG TERM DISCUSSION... UPPER RIDGE OVER THE CENTRAL CONUS WITH TROF OFF THE WEST COAST DOMINATES THE PATTERN FOR MOST OF THE EXTENDED PERIOD. SOUTHWEST FLOW INTO MONTANA WILL CONTINUE TO PUMP VERY HOT AIR NORTHWARD RESULTING IN WELL ABOVE NORMAL TEMPERATURES THROUGH THE END OF THE MONTH. POSITION OF THE UPPER RIDGE SUGGEST THAT MONSOONAL MOISTURE PLUME WILL BE REDIRECTED EASTWARD BEFORE REACHING NORTHEAST MONTANA WITH WEST COAST TROF DRAWING A WEDGE OF DRY AIR INTO THE STATE. SHORTWAVE LIFTING OUT OF THE GREAT BASIN ON WEDNESDAY WILL INTERRUPT THIS MOISTURE PATTERN ALLOWING FOR SOME THUNDERSTORM DEVELOPMENT. BY THE END OF THE WEEK MODELS SUGGEST THE SUPPRESSION OF THE UPPER RIDGE WITH THE WEST COAST TROF BEGINNING TO PUSH EAST. STILL SIGNIFICANT MODEL DIFFERENCES ON HOW OR WHEN THIS WILL HAPPEN BUT EXPECT COOLING TEMPERATURES AND SOME POTENTIAL FOR THUNDERSTORMS WHEN IT DOES. EBERT && .AVIATION... VFR CONDITIONS WILL PREVAIL FOR ALL TAF SITES THROUGHOUT MOST OF THIS TAF CYCLE. AN ISOLATED THUNDERSTORM MAY IMPACT A TAF SITE OVERNIGHT AND AGAIN SUNDAY AFTERNOON AND EVENING. WINDS WILL BE LIGHT AND VARIABLE OVERNIGHT AND BECOME SOUTHERLY WINDS AROUND 10 KNOTS BY MIDDAY SUNDAY. && .GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE. && $$ WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1248 PM CDT FRI AUG 23 2013 .UPDATE... ISSUED AT 539 AM CDT FRI AUG 23 2013 LATEST HRRR AND 06Z GFS ARE COMING IN WETTER TODAY...WHICH IS ALSO BEING BACKED UP BY RADAR TRENDS THAT SHOW INCREASING CONVECTIVE ACTIVITY ACROSS PORTIONS OF OUR FORECAST AREA. SHOWERS AND THUNDERSTORMS REMAIN FAIRLY ISOLATED...BUT MAY LINGER LONGER THIS MORNING THAN ORIGINALLY ANTICIPATED. IN ADDITION...THESE LATEST MODEL RUNS ARE MORE BULLISH ON SEEING AFTERNOON REDEVELOPMENT AND THUS WE MAY NEED TO EVENTUALLY INCLUDE POPS FOR THIS AFTERNOON IF 12Z MODEL RUNS CONTINUE TO TREND TOWARDS NEEDING PRECIPITATION CHANCES. .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 334 AM CDT FRI AUG 23 2013 THE MAIN FORECAST CONCERN THROUGH THE SHORT TERM PERIOD WILL CENTER AROUND THE CHANCE OF RAIN EARLY THIS MORNING...PRIMARILY ACROSS NORTH CENTRAL KANSAS. THERE IS A WEAK SHORT WAVE OVER NORTHEAST COLORADO EARLY THIS MORNING THAT WILL TRACK EAST TODAY ACROSS SOUTHERN NEBRASKA. IN ADDITION...THERE IS A MODEST 850MB JET MAX LOCATED OVER WESTERN KANSAS TO THE EAST OF AN EASTERN COLORADO MCS. NEW THUNDERSTORMS HAVE BEEN FORMING WITHIN THIS LOW LEVEL JET REGION OUT AHEAD OF THE WEAKENING COLORADO MCS. HAVE ADDED POPS ACROSS KANSAS ZONES DUE TO THE DEVELOPING SHOWERS AND THUNDERSTORMS. BELIEVE THESE SHOWERS/THUNDERSTORMS WILL REMAIN FAIRLY ISOLATED AND WILL BEGIN TO DIE OFF BY AROUND OR JUST AFTER SUNRISE AS THE LOW LEVEL JET GRADUALLY DECREASES. THESE SHOWERS ARE NOT BEING WELL MODELED AND SO CONFIDENCE IN WHEN THE CONVECTION WILL FINALLY DIE DOWN IS RATHER MARGINAL. THERE IS SOME POSSIBILITY OF AFTERNOON SHOWERS AND THUNDERSTORMS DESPITE OUR CURRENTLY DRY FORECAST. THE 00Z AND 06Z NAM BOTH TRY TO RE-INITIATE CONVECTION LATE THIS AFTERNOON JUST TO OUR WEST IN ASSOCIATION WITH THE WEAK SHORT WAVE AS IT TRACKS EAST ACROSS NEBRASKA. IN ADDITION...SOME WRF MODELS ALSO INDICATE THE POSSIBILITY OF AFTERNOON CONVECTION ACROSS PORTIONS OF OUR FORECAST AREA. HOWEVER...EXPECT INCREASING TEMPERATURES WITHIN A CAPPING INVERSION AS WIND AT 700MB TURNS SOUTHWEST AND WARMER AIR MOVES IN ALOFT. THE WRF HAS BEEN OVERDOING CONVECTION RECENTLY AND BELIEVE THAT THE THREAT OF AFTERNOON REDEVELOPMENT IS FAIRLY LOW GIVEN THE STRENGTHENING CAP. THEREFORE...HAVE ELECTED TO CONTINUE TO CARRY A DRY FORECAST ACROSS OUR CWA THIS AFTERNOON. HIGH TEMPERATURES TODAY SHOULD BE WARMER AS OUR WIND WILL BE MORE SOUTHERLY TODAY AND TEMPERATURES WILL BE WARMING AT MOST ALL LAYERS OF THE LOWER ATMOSPHERE. HOWEVER...MID TO HIGH CLOUDS...ESPECIALLY THIS MORNING COULD TAMPER THE WARM UP AND WILL GO FOR HIGHS RANGING FROM THE UPPER 80S ACROSS NEBRASKA TO THE 90S ACROSS KANSAS. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 334 AM CDT FRI AUG 23 2013 PRIMARY FORECAST CONCERN THROUGH THE LONG TERM PERIOD LIES WITH TEMPERATURES. MODELS ARE IN GOOD AGREEMENT AT THE START OF THE FORECAST PERIOD...SHOWING UPPER LEVEL HIGH PRESSURE CENTERED OVER ERN OK/KS INTO MISSOURI...WITH AN AREA OF LOW PRESSURE SPINNING JUST OFF THE PAC NW COAST AND TROUGH AXIS EXTENDING SOUTH OFF THE WEST COAST. THE WEAK WAVE PASSING THROUGH THE FLOW STILL LOOKS TO REMAIN FAR ENOUGH NORTH NOT TO HAVE AN IMPACT ON THE CWA. THROUGH THE REST OF THE WEEKEND AND RIGHT ON INTO THE WORK WEEK...GOOD AGREEMENT CONTINUES BETWEEN MODELS WITH THE OVERALL PATTERN...AND THE DRY FORECAST REMAINS. THE UPPER LEVEL RIDGE...ESP DURING THE WORK WEEK...WILL ACTUALLY SLIDE A TOUCH TO THE WEST AS AN UPPER LEVEL DISTURBANCE/TROUGHING DIGS A BIT FURTHER SOUTH TOWARD THE EAST COAST. THIS LOOKS TO PLACE THE UPPER LEVEL HIGH MORE SQUARELY OVER THE AREA...CENTERED OVER KS/PERHAPS NEAR THE KS/NE STATE LINE. ANY DISTURBANCES WOULD SLIDE NORTH OF THE CWA...WITH THE ATMOSPHERE WELL CAPPED. AT THE SURFACE...THE GENERAL PATTERN WILL RESULT IN SOUTHERLY WINDS THROUGH THE ENTIRE FORECAST PERIOD...AS A TROUGH LIES OVER THE HIGH PLAINS WITH WEAK HIGH PRESSURE OFF TO THE EAST. THE WEEKEND LOOKS TO BE BREEZY...ESP SATURDAY...WITH A TIGHTER PRESSURE GRADIENT EXPECTED TO DEVELOP...POTENTIALLY BRINGING SUSTAINED SPEEDS IN THE 20 TO 25 MPH RANGE WITH HIGHER GUSTS. AS FAR AS TEMPERATURES GO...WITH MODELS SHOWING 850MB TEMPS INCREASING INTO THE MID/UPPER 20C RANGE...HIGH TEMPERATURES CWA-WIDE IN THE 90S DONT LOOK TO BE GOING AWAY ANY TIME SOON. ALSO CANT COMPLETELY RULE OUT SOME READINGS NEAR THE 100 DEGREE MARK...ESP IN SWRN LOCATION. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 334 AM CDT FRI AUG 23 2013 THE MAIN FORECAST CONCERN THROUGH THE SHORT TERM PERIOD WILL CENTER AROUND THE CHANCE OF RAIN EARLY THIS MORNING...PRIMARILY ACROSS NORTH CENTRAL KANSAS. THERE IS A WEAK SHORT WAVE OVER NORTHEAST COLORADO EARLY THIS MORNING THAT WILL TRACK EAST TODAY ACROSS SOUTHERN NEBRASKA. IN ADDITION...THERE IS A MODEST 850MB JET MAX LOCATED OVER WESTERN KANSAS TO THE EAST OF AN EASTERN COLORADO MCS. NEW THUNDERSTORMS HAVE BEEN FORMING WITHIN THIS LOW LEVEL JET REGION OUT AHEAD OF THE WEAKENING COLORADO MCS. HAVE ADDED POPS ACROSS KANSAS ZONES DUE TO THE DEVELOPING SHOWERS AND THUNDERSTORMS. BELIEVE THESE SHOWERS/THUNDERSTORMS WILL REMAIN FAIRLY ISOLATED AND WILL BEGIN TO DIE OFF BY AROUND OR JUST AFTER SUNRISE AS THE LOW LEVEL JET GRADUALLY DECREASES. THESE SHOWERS ARE NOT BEING WELL MODELED AND SO CONFIDENCE IN WHEN THE CONVECTION WILL FINALLY DIE DOWN IS RATHER MARGINAL. THERE IS SOME POSSIBILITY OF AFTERNOON SHOWERS AND THUNDERSTORMS DESPITE OUR CURRENTLY DRY FORECAST. THE 00Z AND 06Z NAM BOTH TRY TO RE-INITIATE CONVECTION LATE THIS AFTERNOON JUST TO OUR WEST IN ASSOCIATION WITH THE WEAK SHORT WAVE AS IT TRACKS EAST ACROSS NEBRASKA. IN ADDITION...SOME WRF MODELS ALSO INDICATE THE POSSIBILITY OF AFTERNOON CONVECTION ACROSS PORTIONS OF OUR FORECAST AREA. HOWEVER...EXPECT INCREASING TEMPERATURES WITHIN A CAPPING INVERSION AS WIND AT 700MB TURNS SOUTHWEST AND WARMER AIR MOVES IN ALOFT. THE WRF HAS BEEN OVERDOING CONVECTION RECENTLY AND BELIEVE THAT THE THREAT OF AFTERNOON REDEVELOPMENT IS FAIRLY LOW GIVEN THE STRENGTHENING CAP. THEREFORE...HAVE ELECTED TO CONTINUE TO CARRY A DRY FORECAST ACROSS OUR CWA THIS AFTERNOON. HIGH TEMPERATURES TODAY SHOULD BE WARMER AS OUR WIND WILL BE MORE SOUTHERLY TODAY AND TEMPERATURES WILL BE WARMING AT MOST ALL LAYERS OF THE LOWER ATMOSPHERE. HOWEVER...MID TO HIGH CLOUDS...ESPECIALLY THIS MORNING COULD TAMPER THE WARM UP AND WILL GO FOR HIGHS RANGING FROM THE UPPER 80S ACROSS NEBRASKA TO THE 90S ACROSS KANSAS. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 334 AM CDT FRI AUG 23 2013 PRIMARY FORECAST CONCERN THROUGH THE LONG TERM PERIOD LIES WITH TEMPERATURES. MODELS ARE IN GOOD AGREEMENT AT THE START OF THE FORECAST PERIOD...SHOWING UPPER LEVEL HIGH PRESSURE CENTERED OVER ERN OK/KS INTO MISSOURI...WITH AN AREA OF LOW PRESSURE SPINNING JUST OFF THE PAC NW COAST AND TROUGH AXIS EXTENDING SOUTH OFF THE WEST COAST. THE WEAK WAVE PASSING THROUGH THE FLOW STILL LOOKS TO REMAIN FAR ENOUGH NORTH NOT TO HAVE AN IMPACT ON THE CWA. THROUGH THE REST OF THE WEEKEND AND RIGHT ON INTO THE WORK WEEK...GOOD AGREEMENT CONTINUES BETWEEN MODELS WITH THE OVERALL PATTERN...AND THE DRY FORECAST REMAINS. THE UPPER LEVEL RIDGE...ESP DURING THE WORK WEEK...WILL ACTUALLY SLIDE A TOUCH TO THE WEST AS AN UPPER LEVEL DISTURBANCE/TROUGHING DIGS A BIT FURTHER SOUTH TOWARD THE EAST COAST. THIS LOOKS TO PLACE THE UPPER LEVEL HIGH MORE SQUARELY OVER THE AREA...CENTERED OVER KS/PERHAPS NEAR THE KS/NE STATE LINE. ANY DISTURBANCES WOULD SLIDE NORTH OF THE CWA...WITH THE ATMOSPHERE WELL CAPPED. AT THE SURFACE...THE GENERAL PATTERN WILL RESULT IN SOUTHERLY WINDS THROUGH THE ENTIRE FORECAST PERIOD...AS A TROUGH LIES OVER THE HIGH PLAINS WITH WEAK HIGH PRESSURE OFF TO THE EAST. THE WEEKEND LOOKS TO BE BREEZY...ESP SATURDAY...WITH A TIGHTER PRESSURE GRADIENT EXPECTED TO DEVELOP...POTENTIALLY BRINGING SUSTAINED SPEEDS IN THE 20 TO 25 MPH RANGE WITH HIGHER GUSTS. AS FAR AS TEMPERATURES GO...WITH MODELS SHOWING 850MB TEMPS INCREASING INTO THE MID/UPPER 20C RANGE...HIGH TEMPERATURES CWA-WIDE IN THE 90S DONT LOOK TO BE GOING AWAY ANY TIME SOON. ALSO CANT COMPLETELY RULE OUT SOME READINGS NEAR THE 100 DEGREE MARK...ESP IN SWRN LOCATION. && .AVIATION...(FOR THE 18Z KGRI TAF THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 1245 PM CDT FRI AUG 23 2013 PREVAILING VFR CONDITIONS WILL CONTINUE AT KGRI FOR THE NEXT 24 HOURS...WITH OCCASIONALLY GUSTY SOUTHERLY WINDS CONTINUING THROUGHOUT. EXPECT A LINE OF STORMS STARTING TO DEVELOP ON SATELLITE NEAR LBF...TO CONTINUE TO BUILD AND SHIFT EAST...BUT MODEL GUIDANCE IS NOT PICKING UP ON THIS WELL. LATEST RAP/12Z WRF ARE TRYING TO DEVELOP SOME CONVECTION AND LIFT IT NORTHEAST THROUGH THE LATE AFTERNOON HOURS...BUT EVEN SO...CONFIDENCE IS LOW DUE TO THE DIFFERENCES BETWEEN CURRENT RETURNS AND MODEL DATA THAT IS TRYING TO CAPTURE THIS. LATEST SPC MESO ANALYSIS DOES SHOW MODERATE INSTABILITY BUILDING AHEAD OF THIS LINE...SO DO THINK WE COULD SEE SOME SHRA OR TSRA IN THE VICINITY OF KGRI AS EARLY AS 22Z...BUT WITH CONFIDENCE LOW...DECIDED TO ONLY GO WITH A CB FOR THE TIME BEING. OTHERWISE...ONCE THIS BOUNDARY SHIFTS EAST...CLEARING SKIES AND GUSTY SOUTHERLY WINDS WILL PERSIST THROUGH THE END OF THE VALID TAF PERIOD. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...WESELY SHORT TERM...WESELY LONG TERM...ADO AVIATION...SAR
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1221 PM CDT FRI AUG 23 2013 .AVIATION... 18Z TAFS FOR KOMA...KLNK...AND KOFK. VFR CONDITIONS ARE EXPECTED THROUGH THE TAF CYCLE. SOUTHEAST WINDS AT 10-14KT SHOULD MAINTAIN SPEEDS FOR MOST OF TONIGHT...WITH WINDS INCREASING OUT OF THE SOUTH BY MID-MORNING TO AROUND 15-19KT. SOME INTERMITTENT MID-LEVEL CLOUDS ARE POSSIBLE. COULD SEE A FEW SHOWERS IN NORTHEAST NEB TONIGHT...MAINLY NEAR KOFK...BUT HAVE KEPT MENTION OF TAFS FOR NOW DUE TO LOW CONFIDENCE IN COVERAGE. MAYES && .PREV DISCUSSION... /ISSUED 932 AM CDT FRI AUG 23 2013/ DISCUSSION... UPDATED GRIDS THIS MORNING FOR ONGOING VERY ISOLATED SHOWERS. INCREASED THE DURATION FOR THE REST OF THE MORNING AS SHOWERS ARE HANGING IN THERE. RAP INDICATES BOTH MID-LEVEL LAPSE RATES AND MUCAPE ARE RATHER LIMITED ACROSS THE AREA...AND WITH NO LIGHTNING YET IN THIS ACTIVITY...HAVE REMOVED THUNDER MENTION FOR TODAY. ALSO INCREASED SKY COVER WITH BROKEN TO OVERCAST SKIES OVER MOST OF THE CWA. CHANCE OF SHOWERS...WITH MAYBE AN ISOLATED RUMBLE OF THUNDER...DOES RETURN TONIGHT AS THE LOW-LEVEL JET PICKS UP...MOST LIKELY TO THE NORTHERN CWA...BUT LIKELY WILL BE A BREAK BETWEEN THE ONGOING SHOWERS AND THE OVERNIGHT ACTIVITY. MAYES PREV DISCUSSION... /ISSUED 349 AM CDT FRI AUG 23 2013/ DISCUSSION... STRONG UPPER LEVEL RIDGING WILL DOMINATE THE WEATHER PATTERN FOR NEXT SEVERAL DAYS. THIS WILL KEEP PRECIPITATION CHANCES MEAGER AND TEMPERATURES SOME 8 TO 10 DEGREES ABOVE NORMAL. TODAY AND TONIGHT...THE MAIN FORECAST CONCERN FOR THIS PERIOD WILL BE THE CHANCE FOR PRECIPITATION THIS MORNING AND AGAIN TONIGHT. THE LATEST 88D SCANS SHOW SOME LIGHT SHOWERS ARE DEVELOPING ALONG THE SOUTHEAST NEBRASKA/KANSAS BORDER. THESE SHOWERS SHOULDN`T AMOUNT TO MUCH AND ARE FORCED BY WEAK WARM AIR ADVECTION ALOFT. DECIDED TO MAINTAIN SLIGHT CHANCE POPS THROUGH MID MORNING TO ACCOUNT FOR THIS. FOR TONIGHT...A STRENGTHENING LOW LEVEL JET AND 850MB FRONT WILL ACT TO GENERATE PRECIPITATION ACROSS MUCH OF EASTERN SOUTH DAKOTA...WHICH MAY BRUSH THE NORTHERN HALF OF THE COUNTY WARNING AREA. SATURDAY ONWARD...SOME COMPUTER MODELS WANT TO MAINTAIN SOME OF THE OVERNIGHT PRECIPITATION INTO WESTERN IOWA ON SATURDAY MORNING. IT DOESN`T APPEAR THERE IS MUCH FORCING TO SUPPORT THIS. IN FACT 500MB HEIGHTS ARE ON THE RISE...SO WENT WITH A DRY FORECAST FROM SATURDAY ONWARD. TEMPERATURES WILL REMAIN WARM...LOW TO MID 90S...THROUGH THE REST OF THE FORECAST. WITH DEW POINTS REMAINING STEADY IN THE MID TO UPPER 60S APPARENT TEMPERATURES WILL PUSH 100...WHICH IS BELOW HEAT ADVISORY CRITERIA. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
932 AM CDT FRI AUG 23 2013 .DISCUSSION... UPDATED GRIDS THIS MORNING FOR ONGOING VERY ISOLATED SHOWERS. INCREASED THE DURATION FOR THE REST OF THE MORNING AS SHOWERS ARE HANGING IN THERE. RAP INDICATES BOTH MID-LEVEL LAPSE RATES AND MUCAPE ARE RATHER LIMITED ACROSS THE AREA...AND WITH NO LIGHTNING YET IN THIS ACTIVITY...HAVE REMOVED THUNDER MENTION FOR TODAY. ALSO INCREASED SKY COVER WITH BROKEN TO OVERCAST SKIES OVER MOST OF THE CWA. CHANCE OF SHOWERS...WITH MAYBE AN ISOLATED RUMBLE OF THUNDER...DOES RETURN TONIGHT AS THE LOW-LEVEL JET PICKS UP...MOST LIKELY TO THE NORTHERN CWA...BUT LIKELY WILL BE A BREAK BETWEEN THE ONGOING SHOWERS AND THE OVERNIGHT ACTIVITY. MAYES && .PREV DISCUSSION... /ISSUED 632 AM CDT FRI AUG 23 2013/ AVIATION...12Z TAFS FOR KOFK...KOMA AND KLNK. VFR CONDITIONS ARE EXPECTED THROUGHOUT THE TAF CYCLE. A FEW ISOLATED SHOWERS ARE FLOATING AROUND THE AREA THIS MORNING BUT SHOULD REMAIN ISOLATED ENOUGH TO LEAVE A MENTION OUT OF THE TAFS. EXPECT MORE SCATTERED ACTIVITY TO DEVELOP TOWARD THE END OF THE TAF CYCLE SATURDAY MORNING...BUT DUE TO LACK OF COVERAGE...WILL KEEP OUT OF THIS SET OF TAFS. KERN PREV DISCUSSION... /ISSUED 349 AM CDT FRI AUG 23 2013/ DISCUSSION... STRONG UPPER LEVEL RIDGING WILL DOMINATE THE WEATHER PATTERN FOR NEXT SEVERAL DAYS. THIS WILL KEEP PRECIPITATION CHANCES MEAGER AND TEMPERATURES SOME 8 TO 10 DEGREES ABOVE NORMAL. TODAY AND TONIGHT...THE MAIN FORECAST CONCERN FOR THIS PERIOD WILL BE THE CHANCE FOR PRECIPITATION THIS MORNING AND AGAIN TONIGHT. THE LATEST 88D SCANS SHOW SOME LIGHT SHOWERS ARE DEVELOPING ALONG THE SOUTHEAST NEBRASKA/KANSAS BORDER. THESE SHOWERS SHOULDN`T AMOUNT TO MUCH AND ARE FORCED BY WEAK WARM AIR ADVECTION ALOFT. DECIDED TO MAINTAIN SLIGHT CHANCE POPS THROUGH MID MORNING TO ACCOUNT FOR THIS. FOR TONIGHT...A STRENGTHENING LOW LEVEL JET AND 850MB FRONT WILL ACT TO GENERATE PRECIPITATION ACROSS MUCH OF EASTERN SOUTH DAKOTA...WHICH MAY BRUSH THE NORTHERN HALF OF THE COUNTY WARNING AREA. SATURDAY ONWARD...SOME COMPUTER MODELS WANT TO MAINTAIN SOME OF THE OVERNIGHT PRECIPITATION INTO WESTERN IOWA ON SATURDAY MORNING. IT DOESN`T APPEAR THERE IS MUCH FORCING TO SUPPORT THIS. IN FACT 500MB HEIGHTS ARE ON THE RISE...SO WENT WITH A DRY FORECAST FROM SATURDAY ONWARD. TEMPERATURES WILL REMAIN WARM...LOW TO MID 90S...THROUGH THE REST OF THE FORECAST. WITH DEW POINTS REMAINING STEADY IN THE MID TO UPPER 60S APPARENT TEMPERATURES WILL PUSH 100...WHICH IS BELOW HEAT ADVISORY CRITERIA. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ 99/99
AREA FORECAST DISCUSSION
NWS HASTINGS NE
546 AM CDT FRI AUG 23 2013 .UPDATE... ISSUED AT 539 AM CDT FRI AUG 23 2013 LATEST HRRR AND 06Z GFS ARE COMING IN WETTER TODAY...WHICH IS ALSO BEING BACKED UP BY RADAR TRENDS THAT SHOW INCREASING CONVECTIVE ACTIVITY ACROSS PORTIONS OF OUR FORECAST AREA. SHOWERS AND THUNDERSTORMS REMAIN FAIRLY ISOLATED...BUT MAY LINGER LONGER THIS MORNING THAN ORIGINALLY ANTICIPATED. IN ADDITION...THESE LATEST MODEL RUNS ARE MORE BULLISH ON SEEING AFTERNOON REDEVELOPMENT AND THUS WE MAY NEED TO EVENTUALLY INCLUDE POPS FOR THIS AFTERNOON IF 12Z MODEL RUNS CONTINUE TO TREND TOWARDS NEEDING PRECIPITATION CHANCES. .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 334 AM CDT FRI AUG 23 2013 THE MAIN FORECAST CONCERN THROUGH THE SHORT TERM PERIOD WILL CENTER AROUND THE CHANCE OF RAIN EARLY THIS MORNING...PRIMARILY ACROSS NORTH CENTRAL KANSAS. THERE IS A WEAK SHORT WAVE OVER NORTHEAST COLORADO EARLY THIS MORNING THAT WILL TRACK EAST TODAY ACROSS SOUTHERN NEBRASKA. IN ADDITION...THERE IS A MODEST 850MB JET MAX LOCATED OVER WESTERN KANSAS TO THE EAST OF AN EASTERN COLORADO MCS. NEW THUNDERSTORMS HAVE BEEN FORMING WITHIN THIS LOW LEVEL JET REGION OUT AHEAD OF THE WEAKENING COLORADO MCS. HAVE ADDED POPS ACROSS KANSAS ZONES DUE TO THE DEVELOPING SHOWERS AND THUNDERSTORMS. BELIEVE THESE SHOWERS/THUNDERSTORMS WILL REMAIN FAIRLY ISOLATED AND WILL BEGIN TO DIE OFF BY AROUND OR JUST AFTER SUNRISE AS THE LOW LEVEL JET GRADUALLY DECREASES. THESE SHOWERS ARE NOT BEING WELL MODELED AND SO CONFIDENCE IN WHEN THE CONVECTION WILL FINALLY DIE DOWN IS RATHER MARGINAL. THERE IS SOME POSSIBILITY OF AFTERNOON SHOWERS AND THUNDERSTORMS DESPITE OUR CURRENTLY DRY FORECAST. THE 00Z AND 06Z NAM BOTH TRY TO RE-INITIATE CONVECTION LATE THIS AFTERNOON JUST TO OUR WEST IN ASSOCIATION WITH THE WEAK SHORT WAVE AS IT TRACKS EAST ACROSS NEBRASKA. IN ADDITION...SOME WRF MODELS ALSO INDICATE THE POSSIBILITY OF AFTERNOON CONVECTION ACROSS PORTIONS OF OUR FORECAST AREA. HOWEVER...EXPECT INCREASING TEMPERATURES WITHIN A CAPPING INVERSION AS WIND AT 700MB TURNS SOUTHWEST AND WARMER AIR MOVES IN ALOFT. THE WRF HAS BEEN OVERDOING CONVECTION RECENTLY AND BELIEVE THAT THE THREAT OF AFTERNOON REDEVELOPMENT IS FAIRLY LOW GIVEN THE STRENGTHENING CAP. THEREFORE...HAVE ELECTED TO CONTINUE TO CARRY A DRY FORECAST ACROSS OUR CWA THIS AFTERNOON. HIGH TEMPERATURES TODAY SHOULD BE WARMER AS OUR WIND WILL BE MORE SOUTHERLY TODAY AND TEMPERATURES WILL BE WARMING AT MOST ALL LAYERS OF THE LOWER ATMOSPHERE. HOWEVER...MID TO HIGH CLOUDS...ESPECIALLY THIS MORNING COULD TAMPER THE WARM UP AND WILL GO FOR HIGHS RANGING FROM THE UPPER 80S ACROSS NEBRASKA TO THE 90S ACROSS KANSAS. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 334 AM CDT FRI AUG 23 2013 PRIMARY FORECAST CONCERN THROUGH THE LONG TERM PERIOD LIES WITH TEMPERATURES. MODELS ARE IN GOOD AGREEMENT AT THE START OF THE FORECAST PERIOD...SHOWING UPPER LEVEL HIGH PRESSURE CENTERED OVER ERN OK/KS INTO MISSOURI...WITH AN AREA OF LOW PRESSURE SPINNING JUST OFF THE PAC NW COAST AND TROUGH AXIS EXTENDING SOUTH OFF THE WEST COAST. THE WEAK WAVE PASSING THROUGH THE FLOW STILL LOOKS TO REMAIN FAR ENOUGH NORTH NOT TO HAVE AN IMPACT ON THE CWA. THROUGH THE REST OF THE WEEKEND AND RIGHT ON INTO THE WORK WEEK...GOOD AGREEMENT CONTINUES BETWEEN MODELS WITH THE OVERALL PATTERN...AND THE DRY FORECAST REMAINS. THE UPPER LEVEL RIDGE...ESP DURING THE WORK WEEK...WILL ACTUALLY SLIDE A TOUCH TO THE WEST AS AN UPPER LEVEL DISTURBANCE/TROUGHING DIGS A BIT FURTHER SOUTH TOWARD THE EAST COAST. THIS LOOKS TO PLACE THE UPPER LEVEL HIGH MORE SQUARELY OVER THE AREA...CENTERED OVER KS/PERHAPS NEAR THE KS/NE STATE LINE. ANY DISTURBANCES WOULD SLIDE NORTH OF THE CWA...WITH THE ATMOSPHERE WELL CAPPED. AT THE SURFACE...THE GENERAL PATTERN WILL RESULT IN SOUTHERLY WINDS THROUGH THE ENTIRE FORECAST PERIOD...AS A TROUGH LIES OVER THE HIGH PLAINS WITH WEAK HIGH PRESSURE OFF TO THE EAST. THE WEEKEND LOOKS TO BE BREEZY...ESP SATURDAY...WITH A TIGHTER PRESSURE GRADIENT EXPECTED TO DEVELOP...POTENTIALLY BRINGING SUSTAINED SPEEDS IN THE 20 TO 25 MPH RANGE WITH HIGHER GUSTS. AS FAR AS TEMPERATURES GO...WITH MODELS SHOWING 850MB TEMPS INCREASING INTO THE MID/UPPER 20C RANGE...HIGH TEMPERATURES CWA-WIDE IN THE 90S DONT LOOK TO BE GOING AWAY ANY TIME SOON. ALSO CANT COMPLETELY RULE OUT SOME READINGS NEAR THE 100 DEGREE MARK...ESP IN SWRN LOCATION. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 516 AM CDT FRI AUG 23 2013 THE MAIN THING TO WATCH OUT FOR TODAY WILL BE THE DEVELOPING SHOWERS AND ISOLATED THUNDERSTORMS. LATEST 06Z GFS AND MOST RECENT HRRR MODEL RUN ARE BOTH MORE AGGRESSIVE WITH GETTING PRECIPITATION TODAY. WILL CONTINUE TO LEAVE THUNDER AND PRECIPITATION OUT OF THE TAF FOR NOW...BUT THE TAF MAY NEED TO BE AMENDED DEPENDING ON RADAR TRENDS AND WHERE THESE ISOLATED THUNDERSTORMS DEVELOP. THE WIND WILL REMAIN OUT OF THE SOUTHEAST TODAY AND THEN BECOME MORE SOUTHERLY LATE TONIGHT. EXPECT A SCATTERED TO BROKEN MID DECK OF CLOUDS THROUGH THE MORNING AND POSSIBLY THROUGH MUCH OF THE DAY. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...WESELY SHORT TERM...WESELY LONG TERM...ADO AVIATION...WESELY
AREA FORECAST DISCUSSION...UPDATED
NWS ALBUQUERQUE NM
1118 PM MDT THU AUG 22 2013 .AVIATION... 06Z TAF CYCLE VFR CONDITIONS TO PERSIST THROUGH THE TAF PERIOD OUTSIDE OF ISOLATED SHOWERS AND THUNDERSTORMS ACROSS WESTERN PORTIONS OF THE FORECAST AREA FRIDAY AFTERNOON AND EVENING. TERMINALS MOST LIKELY TO BE IMPACTED ARE KGUP AND KFMN LATE FRIDAY. BRIEF MVFR CONDITIONS LIKELY WITH THUNDERSTORMS FRIDAY AFTERNOON/EVENING. 11 && .PREV DISCUSSION...254 PM MDT THU AUG 22 2013... NOT MUCH CHANGE TO THE FORECAST. AS EXPECTED...EVEN LESS CONVECTION HAS POPPED UP THIS AFTERNOON AS THE DRY WEDGE AHEAD OF THE EASTERLY WAVE MOVES ACROSS THE STATE. ALSO OF NOTE IS A PRETTY HEALTHY INVERSION AROUND 550 MB ON THE 12Z ABQ SOUNDING. BEST CHANCES FOR STORMS FOR THE REST OF THE EVENING WILL BE ACROSS THE NORTHERN MTNS...AND IF THE HRRR IS CORRECT...MOST OF THE PRECIPITATION WILL BE DONE BY 03Z. THE DRY WEDGE SHOULD BE OVER NORTHERN NM TOMORROW. MEANWHILE...THE UPPER HIGH WILL CONTINUE TO CREEP EASTWARD...AND WILL BE CENTERED OVER OK/KS BY TOMORROW AFTN. THIS WILL ALLOW SOME OF THE MOISTURE ASSOCIATED WITH THE EASTERLY WAVE TO CREEP UP INTO NM FRIDAY AFTN/NIGHT. THIS SHOULD ALLOW FOR AN UPTICK IN SHOWER AND THUNDERSTORM COVERAGE ON SATURDAY...MAINLY ACROSS THE HIGHER TERRAIN. BY SUNDAY AFTN...THE UPPER HIGH STRENGTHENS TO 596DAM AND THE WESTWARD EXTENSION OF THE HIGH WILL BUILD BACK INTO NM. THIS WILL KEEP THE BULK OF THE MOISTURE ASSOCIATED WITH AND AHEAD OF NOW TROPICAL DEPRESSION NINE-E TO THE WEST OF THE STATE. INSTEAD...IT APPEARS SOME RELATIVELY DRIER AIR WILL CIRCLE IN OVER NM. THE GFS WANTS TO BRING ANOTHER WEAK WAVE ROUNDING THE SOUTH SIDE OF THE UPPER HIGH INTO THE STATE ON MONDAY. THERE IS SOME MODEST MOISTURE ASSOCIATED WITH THIS... SO THERE MAY BE A FEW MORE STORMS THAN ON SUNDAY. HOWEVER THE ECMWF DOES NOT REALLY SHOW THIS FEATURE OR THE MOISTURE MOVING UP INTO NM UNTIL AT LEAST 24 HOURS LATER. SO FOR NOW...MONDAY-WEDNESDAY LOOKS FAIRLY MINIMAL PRECIPITATION-WISE. LATER IN THE WEEK...MODELS LOOK TO WEAKEN THE WESTWARD EXTENSION OF THE HIGH...WHICH MAY ALLOW FOR SOME RICHER MONSOON MOISTURE TO MOVE INTO WESTERN AND CENTRAL NM...ESPECIALLY IF THERE IS INDEED A SECOND TROPICAL SYSTEM LURKING SOUTH OF THE BAJA AS MODELS ARE INDICATED. 34 .FIRE WEATHER... A MORE STABLE AND DRIER AIRMASS HAS INFILTRATED A LARGE PORTION OF THE FORECAST AREA TODAY. THE RESULT IS ISOLATED SMALLER FOOTPRINTS OF WETTING RAIN. THE STEERING FLOW FOR THE STORMS THE REST OF TODAY WILL BE TOWARDS THE NORTHEAST. THE HEART OF THE DRIER AIRMASS WILL SHIFT TO THE NORTH AND NORTHEAST ON FRIDAY. THUNDERSTORM COVERAGE WILL INCREASE BUT THE WETTING RAIN FOOTPRINT WONT INCREASE TOO MUCH. HIGH TEMPERATURES WILL BE NEAR TO SLIGHTLY BELOW NORMAL SOUTH AND NEAR TO SLIGHTLY ABOVE NORMAL NORTH. VENTILATION RATES WILL BE PRETTY GOOD AS SOUTH/SOUTHEAST WINDS INCREASE ACROSS THE AREA. SOME BREEZES WILL BE OBSERVED ACROSS THE EASTERN PLAINS...ESPECIALLY NORTHEAST WHERE A LEE SURFACE TROUGH STRENGTHENS. THE UPPER HIGH WILL STRENGTHEN AND BECOME DOMINATE OVER THE SOUTHERN PLAINS AND MID MISSISSIPPI VALLEY REGION DURING THE WEEKEND. CONFIDENCE IS PRETTY HIGH FOR THAT PATTERN. DUE TO THE ABOVE NORMAL STRENGTH TO THE UPPER HIGH...THUNDERSTORM COVERAGES WILL VARY. SATURDAY STILL LOOKS TO BE A MORE ACTIVE WETTING THUNDERSTORM DAY. THE CONTINENTAL DIVIDE AND TO A LESSER EXTENT THE CENTRAL MTN CHAIN WOULD BE FAVORED. THERE IS SOME DISCREPANCY IN THE MODELS AS FAR AS CENTRAL MOUNTAINS ARE CONCERNED. STEERING FLOW ON SATURDAY WOULD TAKE THE STORMS TOWARDS THE NORTH AND NORTHEAST. A DRIER AND MORE STABLE AIRMASS PIVOTING AROUND THE UPPER HIGH IS STILL EXPECTED TO INVADE PORTIONS OF THE AREA ON SUNDAY. THE ECMWF/GFS AND NAM MODELS DEPICT THIS. BREEZES WOULD ENHANCE ACROSS THE EASTERN PLAINS DURING THE WEEKEND. THIS IS A RESULT OF AN UNUSUALLY STRONG LEE SIDE SURFACE TROUGH THAT IS EXPECTED TO STRENGTHEN DURING THE PERIOD. THE PEAK WIND PERIOD WOULD BE ON SATURDAY. THE LONGER RANGE MODELS STILL SHOW THE MAIN MONSOONAL PLUME WRAPPING AROUND THE UPPER HIGH OVER ARIZONA AND FAR WEST NEW MEXICO DURING THE EARLIER HALF OF NEXT WEEK. THE DRIER AND MORE STABLE AIRMASS WOULD GET SHIFTED SOME TOWARDS THE EAST SO THUNDERSTORM COVERAGE EACH DAY SHOULD INCREASE SLIGHTLY FROM WEST TO EAST. AGAIN...MAINLY KEEPING STORMS WEST OF THE CENTRAL MTNS AND ESPECIALLY FAVORING THE CONTINENTAL DIVIDE. TEMPERATURES WOULD BE ABOVE NORMAL EAST AND NEAR NORMAL WEST. THE LEE TROUGH WILL REMAIN ACROSS THE EASTERN PLAINS BUT IS EXPECTED TO WEAKEN SOME AS TIME PROGRESSES. THUS LOOK FOR THE OVERALL WIND FLOW TO LESSEN SOME. GUSTY OUTFLOW WINDS WOULD REMAIN A CONCERN HOWEVER...ACROSS WESTERN AND CENTRAL AREAS. THE ECMWF AND GFS REMAINS PRETTY STEADFAST IN KEEPING THE MAIN UPPER HIGH CENTER TO THE EAST OF THE STATE THE LATTER HALF OF NEXT WEEK. THE HIGH ALSO LOOKS TO BE QUITE STRONG AND SIMILAR TO THE STRENGTH AND POSITION IT WAS AUGUST 2011. MOISTURE WOULD CONTINUE TO OOZE EASTWARD DUE TO OUTFLOW BOUNDARIES FROM CONVECTION ACROSS THE WEST BUT THE FAVORED AREAS FOR WETTING RAIN WOULD REMAIN WEST. THE EASTERN PLAINS ONCE AGAIN LOOK TO BE ON THE DRIER AND WARMER SIDE. THE CURING OF NEW GRASS GROWTH ACROSS THE EAST WOULD MOST LIKELY START UP DURING THIS PERIOD. 50 && .ABQ WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 52
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
329 PM EDT FRI AUG 23 2013 .SYNOPSIS... A COLD FRONT WILL CROSS THE AREA LATE TONIGHT INTO SATURDAY MORNING BRINGING SCATTERED SHOWERS AND THUNDERSTORMS. THIS FRONT WILL PUSH SOUTH OF THE AREA DURING SATURDAY...AS HIGH PRESSURE BUILDS DOWN FROM THE NORTH. COOLER AND DRIER CONDITIONS WILL DEVELOP SUNDAY INTO NEXT WEEK. A WARMING TREND WILL TAKE PLACE BY THE MIDDLE OF NEXT WEEK AS HIGH PRESSURE SHIFTS OFFSHORE. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... AS OF 130 PM FRIDAY...CONVECTION HAS STARTED TO DEVELOP IN THE PAST HALF HOUR. AS MENTIONED EARLIER THE MORE ORGANIZED CONVECTION IS EXPECTED AFTER 21 UTC WITH THE APPROACHING SHORT WAVE LOCATED IN NORTHWEST VIRGINIA. THE NAM AND 15 UTC RUC MOVE THIS FEATURE TOWARDS THE AREA JUST AFTER 20 UTC. SO EXPECT TO SEE UNORGANIZED CONVECTION WITH A FEW BOUNDARY INTERACTIONS BEFORE 20 UTC. THEN AS THE HIGH RESOLUTION MODELS ARE SHOWING...A LINE OR LINE SEGMENTS OF CONVECTION...WILL DEVELOP OR ADVECT FROM THE THE NORTHWEST AND INTO THE REGION. TIMING OF THE FRONTAL PASSAGE APPEARS TO BE ALONG A LINE FROM LUMBERTON TO BURGAW BY 06 UTC AND THE FRONT SHIFTS TO A LINE NEAR A MYRTLE BEACH TO KINGSTREE LINE. WITH THIS FRONTAL PASSAGE LOW TEMPERATURES ARE EXPECTED TO REACH THE UPPER 60S IN THE NORTH AND THE LOWER 70S IN THE SOUTH. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/... AS OF 300 PM FRIDAY...COLD FRONT WILL CROSS THE AREA AND BE JUST SOUTH OF THE CWA AT THE START OF THE PERIOD. THIS LEAVES NE FLOW ACROSS THE CWA AS HIGH PRESSURE RIDGES DOWN THE COAST...BECOMING ALIGNED JUST WEST OF THE CWA THROUGH THE WKND. WHILE SATURDAY WILL SHOW SLOW IMPROVEMENTS...LOW LEVEL MOISTURE WILL BE TOUGH TO ERODE...ESPECIALLY NEAR THE COAST. THIS IS ECHOED IN FORECAST PROFILES AND EVIDENT BY WEAK CONTINUATION OF 850-925MB THETA-E RIDGE THROUGH SAT NIGHT. SCHC/ISOLATED SHOWERS WILL BE POSSIBLE THE FIRST HALF OF SATURDAY BEHIND THE FRONT...BUT CLEARING/DRYING WILL OCCUR LATE IN THE DAY...AND PWATS DROP TO ONE INCH OR LESS (PRETTY INCREDIBLE FOR AUGUST) BY SUNDAY MORNING. DRY HIGH PRESSURE ENVELOPS THE AREA SUNDAY...AND A BEAUTIFUL LATE-SUMMER DAY ON TAP WITH AMPLE SUNSHINE AND WARM BUT BELOW NORMAL TEMPS. HIGHS THROUGH THE WKND WILL BE ONLY IN THE LOW/MID 80S...COOLER SUNDAY...WITH LOWS FALLING INTO THE LOW 60S...WITH POSSIBLY A FEW 58S AND 59S SUNDAY NIGHT IN THE COLD SPOTS THANKS TO THIS INCREDIBLY DRY AIR MASS! && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 3 PM FRIDAY...LARGE UPPER LEVEL RIDGE OVER THE CENTER OF THE NATION ON MONDAY. A SLIGHT RETROGRESSION OF THIS FEATURE WILL ALLOW FOR A NW FLOW TO DEVELOP LOCALLY BY MID WEEK...ONLY TO BE STRENGTHENED THURSDAY AND FRIDAY AS AN UPPER TROUGH FORMS OFF THE NEW ENGLAND COAST. SURFACE HIGH PRESSURE BUILDING IN FROM THE NORTH WILL KEEP TEMPS A LITTLE BELOW CLIMO UNTIL AROUND WEDNESDAY WHEN THE CENTER OF THE WEAKENING HIGH DRIFTS TO OUR SOUTH AND A PIEDMONT TROUGH DEVELOPS. THE LATE PERIOD SHARPENING OF THE UPPER TROUGH DRIVES A COOL FRONT THROUGH ON THURSDAY. MODELS SHOWING A FAIR AMOUNT OF PRECIP WITH ITS PASSAGE BUT GIVEN THE NEARLY NONEXISTENT MOISTURE FLUX AHEAD OF IT PREFER TO KEEP POPS AT SLIGHT CHANCE. && .AVIATION /20Z FRIDAY THROUGH WEDNESDAY/... AS OF 18Z...A COLD FRONT WILL DROP SOUTHEAST THIS AFTERNOON...WITH MODERATE CONFIDENCE FOR A BAND OF CONVECTION ON THE LEADING EDGE. MODERATE CONVERGENCE AND MODERATE TO STRONG CAPE SHOULD PRODUCE THUNDERSTORMS WITH GUSTY WINDS AS THEY DROP SOUTHEAST AROUND 20 MPH. SMALL HAIL COULD ALSO OCCUR...GIVEN THE NORTHWEST FLOW. TIMING MAY BE A BIT FAST AT THIS TIME...BUT FEEL THIS COULD BE MORE SQUALLY IN NATURE...AND THEY TEND TO OUTRUN THEIR SUPPORT. THERE WILL PROBABLY BE SEVERAL HOURS OF LIGHT SHOWERS BEHIND THE FRONT. WINDS WILL SHIFT FROM SOUTHWEST TO WEST NORTHWEST AS THE STORMS MOVE IN. CEILINGS WILL BE VFR FOR THE MOST PART...WITH SOME BRIEF IFR VISIBILITIES IN THE HEAVIER CONVECTION. OVERNIGHT...WINDS WILL CONTINUE TO VEER TO THE NORTHWEST AS THE RAIN SLOWLY ENDS AFTER 05Z. A POST FRONTAL VFR STRATA CU CEILING IS EXPECTED. SATURDAY...VFR WITH A CONTINUED STRATA CU CEILING AND LIGHT NORTHERLY WINDS. EXTENDED OUTLOOK...VFR SATURDAY AFTERNOON THROUGH MONDAY. SCATTERED CONVECTION TUESDAY AND WEDNESDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 130 PM FRIDAY...WEST TO SOUTHWESTERLY WINDS OF 10 TO 15 KNOTS ARE BLOWING OVER THE WATERS THIS AFTERNOON. AS A FRONTAL BOUNDARY NEARING THE VIRGINIA AND NORTH CAROLINA BORDER SHIFTS SOUTHWARD WINDS WILL BECOME MORE SOUTHWESTERLY THROUGH THE EVENING. THE WIND SHIFT WITH THE FRONT IS EXPECTED TO BEGIN JUST AFTER 06 UTC NEAR SURF CITY AND AFTER 12 UTC BY THE LOWER SANTEE RIVER. SEAS ARE EXPECTED TO REMAIN IN THE 2 TO 3 FOOT RANGE THROUGH SATURDAY MORNING. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 300 PM FRIDAY...COLD FRONT SOUTH OF THE AREA AT THE START OF THE PERIOD WILL PUSH FURTHER SOUTH THROUGH THE DAY IN RESPONSE TO A HIGH PRESSURE BUILDING SOUTH FROM NEW ENGLAND. HIGH PRESSURE AXIS REMAINS WEST OF THE LOCAL AREA...SO WATERS BECOME ALIGNED WITHIN A PINCHED GRADIENT AND A NE SURGE DEVELOPS LATE SATURDAY AND MUCH OF SUNDAY. WINDS INCREASE FROM NORTH AT 10 KTS TO START THE PERIOD...TO NE UP TO 20 KTS ON SUNDAY...BEFORE FALLING BACK TO NE AT 10-15 KTS LATE. SEAS BUILD IN RESPONSE TO THE INCREASING WINDS...FROM 2-3 FT SATURDAY UP TO 3-5 FT SUNDAY...AND A SCEC WILL LIKELY BE NEEDED FOR THE WATERS THE SECOND HALF OF THE SHORT TERM. LONG TERM /MONDAY THROUGH WEDNESDAY/... AS OF 3 PM FRIDAY...BROAD SWATH OF NE WINDS ALONG THE SOUTHEAST COAST ON MONDAY AS HIGH PRESSURE DIVES IN FROM POINTS NORTH. THE FLOW WILL EASE AS THE DAY WEARS ON AND THE GRADIENT RELAXES. WIND WILL TURN LIGHT AND VARIABLE MONDAY NIGHT AND THEN A SOUTHERLY COMPONENT BECOMES PREDOMINANT ON TUESDAY DUE TO FORMATION OF A PIEDMONT TROUGH. SW FLOW INCREASES ON WEDNESDAY ALLOWING FOR BUILDING SEAS. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...JDW NEAR TERM...DRH SHORT TERM...JDW LONG TERM...MBB AVIATION...DRH MARINE...JDW/MBB/DRH
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
131 PM EDT FRI AUG 23 2013 .SYNOPSIS... A COLD FRONT APPROACHING FROM THE NORTHWEST THIS EVENING WILL PUSH SOUTH OF THE AREA BY EARLY SATURDAY. THE COLD FRONT WILL USHER IN COOLER AND DRIER CONDITIONS FOR THE WEEKEND INTO EARLY NEXT WEEK. A WARMING TREND WILL TAKE PLACE BY THE MIDDLE OF NEXT WEEK AS HIGH PRESSURE SHIFTS OFFSHORE AND COLD FRONT APPROACHES THE CAROLINAS FROM THE NORTHWEST. && .NEAR TERM /THROUGH TONIGHT/... AS OF 130 PM FRIDAY...CONVECTION HAS STARTED TO DEVELOP IN THE PAST HALF HOUR. AS MENTIONED EARLIER THE MORE ORGANIZED CONVECTION IS EXPECTED AFTER 21 UTC WITH THE APPROACHING SHORT WAVE LOCATED IN NORTHWEST VIRGINIA. THE NAM AND 15 UTC RUC MOVE THIS FEATURE TOWARDS THE AREA JUST AFTER 20 UTC. SO EXPECT TO SEE UNORGANIZED CONVECTION WITH A FEW BOUNDARY INTERACTIONS BEFORE 20 UTC. THEN AS THE HIGH RESOLUTION MODELS ARE SHOWING A LINE OR LINE SEGMENTS OF CONVECTION DEVELOPING OR ADVECT FROM THE THE NORTHWEST AND INTO THE REGION. TIMING OF THE FRONTAL PASSAGE APPEARS TO BE ALONG A LINE FROM LUMBERTON TO BURGAW BY 06 UTC AND THE FRONT SHIFTS TO A LINE NEAR A MYRTLE BEACH TO KINGSTREE LINE. WITH THIS FRONTAL PASSAGE LOW TEMPERATURES ARE EXPECTED TO REACH THE UPPER 60S IN THE NORTH AND THE LOWER 70S IN THE SOUTH. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 3 AM FRIDAY...THE H5 TROUGH WILL PUSH FRONT SOUTH BY SAT MORNING...BUT WILL KEEP POTENTIAL FOR SHWRS ON SAT WITH BEST CONVERGENCE FROM THE TIP OF CAPE FEAR SOUTH...WHERE BEST CONVERGENCE AND RESIDUAL MOISTURE WILL BE. DEEP N-NW FLOW DEVELOPING BEHIND FRONT AS MID TO UPPER TROUGH AXIS SHIFTS FARTHER OFF THE COAST AND HIGH PRESSURE BUILDS IN THROUGH SATURDAY. PCP WATER VALUES WILL DROP FROM CLOSE TO 2 INCHES AHEAD OF FRONT TO LESS THAN AN INCH BY END OF PERIOD OR EARLY SUNDAY. THEREFORE EXPECT CLEARING THROUGH SAT NIGHT FROM NORTH TO SOUTH. RESIDUAL LOW LEVEL MOISTURE FROM PCP MAY PRODUCE FOG ACROSS THE AREA SAT NIGHT. HIGHS SATURDAY WILL REACH INTO THE LOW 80S AFTER A FAIRLY WARM START DUE TO CLOUDS AND SHOWERS ASSOCIATED WITH THE COLD FRONT. LOWS SATURDAY NIGHT WILL FALL DOWN INTO THE 60S AS A MUCH DRIER AIRMASS MOVES INTO THE REGION. SUNDAY WILL RUN BELOW NORMAL AS RELATIVELY COOLER AND DRIER AIR MASS BUILDS DOWN OVER AREA. && .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 300 AM FRIDAY...RIDGE PUSHES IN FROM THE WEST THROUGH THE MID TO UPPER LEVELS WHILE HIGH PRESSURE NOSES DOWN FROM THE NORTH MONDAY AS IT SHIFTS EAST OFF THE MID ATLANTIC COAST THROUGH TUESDAY. THE RIDGE RETREATS WESTWARD THROUGH MID WEEK AS SHORTWAVES RIDE AROUND IT REACHING INTO THE SOUTHEAST ON WEDNESDAY AS IT PUSHES A COLD FRONT SOUTHEAST. THIS MAY PRODUCE INCREASED CLOUDS AND CHC OF SHWRS ON WED BEFORE HIGH PRESSURE BUILDS IN BEHIND IT BY LATE THURS INTO FRI. OVERALL EXPECT PLENTY OF SUNSHINE WITH TEMPS MODERATING FROM BELOW NORMAL MONDAY TO ABOVE NORMAL BY WED AS MID TO UPPER RIDGE BUILDS EAST INTO THE CAROLINAS PRODUCING H5 HEIGHT RISES. GRADIENT WINDS WILL WEAKEN AS HIGH SHIFTS SOUTH AND EAST WITH MAINLY DIURNAL SHIFTS DUE TO SEA BREEZE/LAND BREEZE. 850 TEMPS WILL BOTTOM OUT AROUND 13C IN COOLER AIR ADVECTING IN BEHIND FRONT AND WILL RISE UP TO 18C BY TUES INTO WED. THE DIURNAL SWINGS IN TEMPS WILL BE FAIRLY LARGE WITH DRY AIR IN PLACE AND DEWPOINT TEMPS REACHING DOWN INTO THE 50S OVER NORTHERN TIER ZONES MONDAY AND TUES. AS HIGH PRESSURE SHIFTS OFF SHORE AND COLD FRONT MAKES ITS WAY SOUTHEAST BY WED EXPECT WARMER SOUTHERLY FLOW BRINGING TEMPS BACK UP TOWARD NORMAL WITH READINGS IN THE MID 80S AND AROUND 90 BY THURS. && .AVIATION /18Z FRIDAY THROUGH TUESDAY/... AS OF 18Z...A COLD FRONT WILL DROP SOUTHEAST THIS AFTERNOON...WITH MODERATE CONFIDENCE FOR A BAND OF CONVECTION ON THE LEADING EDGE. MODERATE CONVERGENCE AND MODERATE TO STRONG CAPE SHOULD PRODUCE THUNDERSTORMS WITH GUSTY WINDS AS THEY DROP SOUTHEAST AROUND 20 MPH. SMALL HAIL COULD ALSO OCCUR...GIVEN THE NORTHWEST FLOW. TIMING MAY BE A BIT FAST AT THIS TIME...BUT FEEL THIS COULD BE MORE SQUALLY IN NATURE...AND THEY TEND TO OUTRUN THEIR SUPPORT. THERE WILL PROBABLY BE SEVERAL HOURS OF LIGHT SHOWERS BEHIND THE FRONT. WINDS WILL SHIFT FROM SOUTHWEST TO WEST NORTHWEST AS THE STORMS MOVE IN. CEILINGS WILL BE VFR FOR THE MOST PART...WITH SOME BRIEF IFR VISIBILITIES IN THE HEAVIER CONVECTION. OVERNIGHT...WINDS WILL CONTINUE TO VEER TO THE NORTHWEST AS THE RAIN SLOWLY ENDS AFTER 05Z. A POST FRONTAL VFR STRATA CU CEILING IS EXPECTED. SATURDAY...VFR WITH A CONTINUED STRATA CU CEILING AND LIGHT NORTHERLY WINDS. EXTENDED OUTLOOK...VFR SATURDAY AFTERNOON THROUGH MONDAY. SCATTERED CONVECTION TUESDAY AND WEDNESDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 130 PM FRIDAY...WEST TO SOUTHWESTERLY WINDS OF 10 TO 15 KNOTS ARE BLOWING OVER THE WATERS THIS AFTERNOON. AS A FRONTAL BOUNDARY NEARING THE VIRGINIA AND NORTH CAROLINA BORDER SHIFTS SOUTHWARD WINDS WILL BECOME MORE SOUTHWESTERLY THROUGH THE EVENING. THE WIND SHIFT WITH THE FRONT IS EXPECTED TO BEGIN JUST AFTER 06 UTC NEAR SURF CITY AND AFTER 12 UTC BY THE LOWER SANTEE RIVER. SEAS ARE EXPECTED TO REMAIN IN THE 2 TO 3 FOOT RANGE THROUGH SATURDAY MORNING. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 3 AM FRIDAY...WINDS WILL SHIFT RAPIDLY TO THE NORTH SATURDAY MORNING BEHIND COLD FRONT. WINDS MAY INCREASE UP TO A SOLID 15 KTS OR POSSIBLY UP TO 20 KTS OVERNIGHT SATURDAY INTO SUNDAY IN NORTHEAST SURGE BEHIND FRONT. SEAS WILL INCREASE IN NORTHEAST SURGE BEHIND FRONT THROUGH SATURDAY NIGHT INTO THE LATTER HALF OF THE WEEKEND...FROM 2 TO 3 FT WITH 2 TO 4 FT RANGE LATE SATURDAY AND MAYBE SLIGHTLY HIGHER AS CAA INCREASES. LONG TERM /MONDAY THROUGH TUESDAY/... AS OF 3 AM FRIDAY...THE WINDS WILL LIGHTEN AS HIGH PRESSURE SHIFTS SOUTH AND WEAKENS AND AIR MASS BEGINS TO MODIFY THROUGH LATE MONDAY. OVERALL SEAS WILL BE 2 TO 4 FT MOST WATERS. A FURTHER SHIFTING OF THE HIGH TO BASICALLY OVERHEAD WILL LEAD TO WINDS BASICALLY LIGHT AND VARIABLE TUESDAY. OVERALL SEAS WILL TREND DOWN TO AROUND TWO FEET TUESDAY. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...HAWKINS SHORT TERM...RGZ LONG TERM...RGZ AVIATION...DL
AREA FORECAST DISCUSSION
NWS RALEIGH NC
252 AM EDT FRI AUG 23 2013 .SYNOPSIS... A COLD FRONT WILL APPROACH FROM THE NORTH THIS AFTERNOON...THEN PUSH SOUTH THROUGH THE REGION TONIGHT AS AN UPPER LEVEL TROUGH DIGS SOUTHEAST ACROSS THE MID ATLANTIC. COOL AND DRY HIGH PRESSURE WILL BUILD INTO THE CAROLINAS FROM THE NORTH IN THE WAKE OF THE COLD FRONT ON SATURDAY AND SUNDAY. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... AS OF 945 PM THURSDAY... SEVERAL CLUSTERS OF PROBLEMATIC STORMS HAVE AFFECTED MAINLY THE EASTERN CWA SINCE LATE AFTERNOON... BUT ISOLATED STORM CLUSTERS PERSIST AROUND THE ENTIRE AREA AS A MODERATELY UNSTABLE AIR MASS (MLCAPE VALUES STILL 1500-2000 J/KG) LINGERS. DEEP LAYER SHEAR REMAINS RESPECTABLE AT 25-30 KTS IN THE BASE OF THE MID LEVEL SHORTWAVE TROUGH NOW SWINGING THROUGH NY/DE/ERN VA/ERN NC... BUT THIS SHOULD BE WANING OVERNIGHT AS THE TROUGH PROGRESSES OFFSHORE. INSTABILITY IS LIKEWISE EXPECTED TO FALL BELOW 1000 J/KG OVERNIGHT... AND WITH PRECIP WATER VALUES HAVING DROPPED TO AT OR UNDER 1.5 INCHES OVER MUCH OF CENTRAL NC ACCORDING TO BLENDED TPW IMAGERY... WE SHOULD SEE EVEN THE ISOLATED STORM CLUSTERS LESSEN IN COVERAGE AND INTENSITY OVER THE NEXT SEVERAL HOURS AS WE LOSE BOTH DYNAMIC AND THERMODYNAMIC SUPPORT. WILL RETAIN THE ISOLATED STORM MENTION FOR ANOTHER FEW HOURS BEFORE DROPPING SHOWER/STORM CHANCES TO UNDER 15 PERCENT LATE TONIGHT. THIS FOLLOWS RECENT HRRR MODEL OUTPUT TRENDS. FAIR TO PARTLY CLOUDY SKIES AND LIGHT WINDS WILL FACILITATE PATCHY FOG DEVELOPMENT LATE. LOW 68-72... IN LINE WITH STATISTICAL GUIDANCE AND PERSISTENCE. -GIH && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 239 AM FRIDAY... MUCH DRIER AND COOLER AIR WILL OVERSPREAD THE REGION THIS WEEKEND COURTESY OF THE MODERATELY STRONG SURFACE HIGH PRESSURE (1026+ MB) THAT WILL BUILD FROM NEW ENGLAND DOWN THE ATLANTIC SEABOARD INTO SC/GA THROUGH SUNDAY NIGHT. THE ONLY ISSUE REALLY WILL BE THE AMOUNT OF CLOUDINESS THAT WILL AFFECT OUR REGION SATURDAY. MODELS AGREE IN PUSHING THE COLD FRONT WELL THROUGH THE REGION BY 12Z/SAT. DAA/CAA WILL OCCUR WITH THE NE FLOW AT THE SURFACE. HOWEVER... SOME MODEL SOLUTIONS INDICATE A TEMPERATURE INVERSION WITH MOISTURE BECOMING TRAPPED UNDER THAT INVERSION IMMEDIATELY BEHIND THE FRONT SATURDAY MORNING INTO THE EARLY AFTERNOON. ALTHOUGH MEASURABLE RAIN IS NOT EXPECTED... VARIABLY CLOUDY SKIES SHOULD RESULT ESPECIALLY IN THE SOUTH AND WEST THROUGH SATURDAY AFTERNOON. EXPECT DECREASING CLOUDINESS FROM N TO S SAT AFTERNOON INTO SAT NIGHT. MOSTLY SUNNY SKIES SUNDAY. HIGHS 80-85 BOTH DAYS. LOWS 55-63 SUNDAY AND MONDAY. && .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 239 AM FRIDAY... THE BUILDING UPPER RIDGE OVER THE MID-MISSISSIPPI VALLEY NEXT WEEK POSES A BIT OF A PROBLEM FOR OUR REGION... THE RETURN OF THE NW FLOW ALOFT. THIS SHOULD BE MOST PRONOUNCED TUESDAY AND BEYOND WHEN SEVERAL VORTICITY MAXIMUMS IN THE NW FLOW (WHICH WILL BE HARD TO TIME) MAY AFFECT OUR REGION. EXPECT INCREASING HEAT... HUMIDITY... AND THE CHANCE OF THUNDERSTORMS MID TO LATE WEEK. STILL... NO HEAT WAVE CONDITIONS ARE ANTICIPATED ALONG OR EAST OF THE APPALACHIANS WITH THIS PATTERN. MONDAY... MOSTLY SUNNY. LOWS 55-62. HIGHS 80-85. TUESDAY AND WEDNESDAY... PARTLY SUNNY. A SLIGHT CHANCE OF AFTERNOON AND EVENING THUNDERSTORMS IN THE NW TUESDAY... THEN A CHANCE ALL ZONES WEDNESDAY AND THURSDAY. LOWS MODERATING INTO THE LOWER 70S BY THURSDAY. HIGHS 85-90. && .AVIATION /06Z FRIDAY THROUGH WEDNESDAY/... AS OF 230 AM FRIDAY... 24-HR TAF PERIOD: ANTICIPATE A CHANCE FOR MVFR FOG AT ALL TAF SITES BETWEEN 08-11Z THIS MORNING. OTHERWISE...EXPECT VFR CONDITIONS TO PREVAIL THROUGH EARLY AFTERNOON. SCATTERED SHOWERS AND THUNDERSTORMS ARE ANTICIPATED TO DEVELOP BY EARLY/MID AFTERNOON IN ADVANCE OF AN UPPER LEVEL DISTURBANCE AND ASSOCIATED COLD FRONT APPROACHING THE REGION FROM THE NORTHWEST...WITH SCATTERED CONVECTION TRACKING SOUTHEAST ACROSS CENTRAL NC DURING THE MID/LATE AFTERNOON (18-00Z) HOURS. ALL TAF SITES WILL LIKELY BE AFFECTED BY CONVECTION...THOUGH THE TERMINALS WITH THE BEST OVERALL CHANCE FOR SHOWERS/STORMS (AND BEST CHANCE FOR AN ISOLD SEVERE STORM) WILL BE RDU/RWI/FAY. WINDS WILL VEER FROM W/NW TO NORTHEAST AT 5-10 KT IN THE WAKE OF THE FRONT BETWEEN SUNSET AND MIDNIGHT...OR THE 00-04Z TIME FRAME. A BRIEF PERIOD OF MVFR/IFR CEILINGS CANNOT BE RULED OUT OVERNIGHT BETWEEN 04-12Z SAT AS LOW-LEVEL FLOW INITIALLY STRENGTHENS OUT OF THE NORTHEAST...THOUGH PROBABILITIES ARE TOO LOW TO MENTION AND ANY SUB-VFR CEILINGS WOULD BE SHORT-LIVED AS A MUCH DRIER AIRMASS ADVECTS INTO CENTRAL NC BY OR SHORTLY AFTER SUNRISE SAT. LOOKING AHEAD: EXCELLENT (VFR) AVIATION CONDITIONS WILL PREVAIL SAT-MON IN ASSOC/W DRY HIGH PRESSURE EXTENDING INTO AND EVENTUALLY SETTLING OVER THE CAROLINAS FROM THE NORTH. A BRIEF PERIOD OF SUB-VFR FOG CANNOT BE RULED OUT AROUND SUNRISE MONDAY MORNING. ANTICIPATE AN INCREASING CHANCE FOR PRIMARILY AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS TUE-THU. -VINCENT && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...HARTFIELD SHORT TERM...BADGETT LONG TERM...BADGETT AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
239 AM EDT FRI AUG 23 2013 .SYNOPSIS... A PRE-FRONTAL TROUGH WILL LINGER OVER THE REGION TODAY. A COLD FRONT WILL PUSH SOUTH THROUGH NORTH CAROLINA FRIDAY NIGHT AND EARLY SATURDAY. HIGH PRESSURE WILL BRING COOLER AND DRIER AIR FOR THE WEEKEND INTO EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... AS OF 945 PM THURSDAY... SEVERAL CLUSTERS OF PROBLEMATIC STORMS HAVE AFFECTED MAINLY THE EASTERN CWA SINCE LATE AFTERNOON... BUT ISOLATED STORM CLUSTERS PERSIST AROUND THE ENTIRE AREA AS A MODERATELY UNSTABLE AIR MASS (MLCAPE VALUES STILL 1500-2000 J/KG) LINGERS. DEEP LAYER SHEAR REMAINS RESPECTABLE AT 25-30 KTS IN THE BASE OF THE MID LEVEL SHORTWAVE TROUGH NOW SWINGING THROUGH NY/DE/ERN VA/ERN NC... BUT THIS SHOULD BE WANING OVERNIGHT AS THE TROUGH PROGRESSES OFFSHORE. INSTABILITY IS LIKEWISE EXPECTED TO FALL BELOW 1000 J/KG OVERNIGHT... AND WITH PRECIP WATER VALUES HAVING DROPPED TO AT OR UNDER 1.5 INCHES OVER MUCH OF CENTRAL NC ACCORDING TO BLENDED TPW IMAGERY... WE SHOULD SEE EVEN THE ISOLATED STORM CLUSTERS LESSEN IN COVERAGE AND INTENSITY OVER THE NEXT SEVERAL HOURS AS WE LOSE BOTH DYNAMIC AND THERMODYNAMIC SUPPORT. WILL RETAIN THE ISOLATED STORM MENTION FOR ANOTHER FEW HOURS BEFORE DROPPING SHOWER/STORM CHANCES TO UNDER 15 PERCENT LATE TONIGHT. THIS FOLLOWS RECENT HRRR MODEL OUTPUT TRENDS. FAIR TO PARTLY CLOUDY SKIES AND LIGHT WINDS WILL FACILITATE PATCHY FOG DEVELOPMENT LATE. LOW 68-72... IN LINE WITH STATISTICAL GUIDANCE AND PERSISTENCE. -GIH && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 239 AM FRIDAY... MUCH DRIER AND COOLER AIR WILL OVERSPREAD THE REGION THIS WEEKEND COURTESY OF THE MODERATELY STRONG SURFACE HIGH PRESSURE (1026+ MB) THAT WILL BUILD FROM NEW ENGLAND DOWN THE ATLANTIC SEABOARD INTO SC/GA THROUGH SUNDAY NIGHT. THE ONLY ISSUE REALLY WILL BE THE AMOUNT OF CLOUDINESS THAT WILL AFFECT OUR REGION SATURDAY. MODELS AGREE IN PUSHING THE COLD FRONT WELL THROUGH THE REGION BY 12Z/SAT. DAA/CAA WILL OCCUR WITH THE NE FLOW AT THE SURFACE. HOWEVER... SOME MODEL SOLUTIONS INDICATE A TEMPERATURE INVERSION WITH MOISTURE BECOMING TRAPPED UNDER THAT INVERSION IMMEDIATELY BEHIND THE FRONT SATURDAY MORNING INTO THE EARLY AFTERNOON. ALTHOUGH MEASURABLE RAIN IS NOT EXPECTED... VARIABLY CLOUDY SKIES SHOULD RESULT ESPECIALLY IN THE SOUTH AND WEST THROUGH SATURDAY AFTERNOON. EXPECT DECREASING CLOUDINESS FROM N TO S SAT AFTERNOON INTO SAT NIGHT. MOSTLY SUNNY SKIES SUNDAY. HIGHS 80-85 BOTH DAYS. LOWS 55-63 SUNDAY AND MONDAY. && .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 239 AM FRIDAY... THE BUILDING UPPER RIDGE OVER THE MID-MISSISSIPPI VALLEY NEXT WEEK POSES A BIT OF A PROBLEM FOR OUR REGION... THE RETURN OF THE NW FLOW ALOFT. THIS SHOULD BE MOST PRONOUNCED TUESDAY AND BEYOND WHEN SEVERAL VORTICITY MAXIMUMS IN THE NW FLOW (WHICH WILL BE HARD TO TIME) MAY AFFECT OUR REGION. EXPECT INCREASING HEAT... HUMIDITY... AND THE CHANCE OF THUNDERSTORMS MID TO LATE WEEK. STILL... NO HEAT WAVE CONDITIONS ARE ANTICIPATED ALONG OR EAST OF THE APPALACHIANS WITH THIS PATTERN. MONDAY... MOSTLY SUNNY. LOWS 55-62. HIGHS 80-85. TUESDAY AND WEDNESDAY... PARTLY SUNNY. A SLIGHT CHANCE OF AFTERNOON AND EVENING THUNDERSTORMS IN THE NW TUESDAY... THEN A CHANCE ALL ZONES WEDNESDAY AND THURSDAY. LOWS MODERATING INTO THE LOWER 70S BY THURSDAY. HIGHS 85-90. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... AS OF 730 PM THURSDAY... A SURFACE TROUGH...AS WELL AS VARIOUS OUTFLOW BOUNDARIES...AND LINGERING INSTABILITY ARE KEEPING A FEW STORMS GOING AROUND CENTRAL NC THIS EVENING...THOUGH MOST OF THE STORMS ARE OCCURRING AWAY FROM TAF SITES AND SHOULD COME TO AN END BY MIDNIGHT. A LIGHT WEST-SOUTHWESTERLY SURFACE WIND AND MOSTLY VFR CONDITIONS ARE EXPECTED...THOUGH A FEW AREAS MAY SEE MVFR VSBYS BY DAYBREAK. AN APPROACHING COLD FRONT WILL INITIATE SCATTERED STORMS BY EARLY FRIDAY AFTERNOON...FIRST AROUND THE TRIAD THEN MOVING SOUTH AND EAST TOWARD KRDU..KRWI AND KFAY. THE OCCURRENCE AND TIMING OF STORMS AT INDIVIDUAL TERMINALS IS STILL UNCERTAIN AT THIS POINT...BUT THE PRESENCE OF THE COLD FRONT AND UPPER LEVEL TROUGH LENDS ENOUGH FORECAST CONFIDENCE FOR A MENTION OF THUNDERSTORMS IN THE TAFS AFTER 18Z. LOOKING AHEAD: AFTER THE PASSAGE OF THE COLD FRONT...HIGH PRESSURE WILL SLOWLY BUILD INTO THE REGION AND STRENGTHEN...LEADING TO A TREND TOWARD VFR CONDITIONS THROUGH EARLY NEXT WEEK. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BADGETT NEAR TERM...HARTFIELD SHORT TERM...BADGETT LONG TERM...BADGETT AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS TULSA OK
1227 PM CDT FRI AUG 23 2013 .DISCUSSION... THE 18Z TAF DISCUSSION IS INCLUDED BELOW. && .AVIATION... CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM. BAND OF HIGH BASED SHOWERS SHOULD DISSIPATE BY 19 OR 20Z...AND VFR CONDITIONS WILL PREVAIL AT ALL TAF SITES THRU MUCH OF THE PERIOD. A STRAY SHOWER OR STORM COULD IMPACT ANY AIRPORT...BUT CHANCES ARE TOO LOW TO MENTION. PERSISTENCE SUGGESTS FOG WILL REDUCE VSBYS AT KBVO AND KFYV DOWN TO IFR RANGE ANYWHERE FROM 06Z TO 14Z TONIGHT AND EARLY SATURDAY. LACY && .PREV DISCUSSION... /ISSUED 907 AM CDT FRI AUG 23 2013/ DISCUSSION... UPPER AIR DATA AT 12Z SHOWS COOLER AND MORE MOIST CONDITIONS IN THE MID LVLS COMPARED TO 24 HRS AGO...FROM 700MB UP TO 500MB. IN THE LATE NIGHT AND EARLY MORNING...THIS MID LVL MOISTURE CREATES SOME INSTABILITY DUE TO NOCTURNAL COOLING ABOVE THIS MOIST LAYER. THIS HAS PRODUCED A FEW HIGH BASED SHOWERS AND A LIGHTNING STRIKE OR TWO OVER EASTERN OKLAHOMA. HOWEVER...AS THE DAY CONTINUES THIS MID LEVEL INSTABILITY WANES AND THUS THE SHOWERS SHOULD DISSIPATE BY MIDDAY AS THE HRRR AND LOCAL WRF MODEL SUGGEST. GRIDS HAVE BEEN UPDATED TO ACCOUNT FOR THE SMALL AREA OF PRECIP DOWN OVER EAST CENTRAL OKLAHOMA. LACY PREV DISCUSSION... /ISSUED 709 AM CDT FRI AUG 23 2013/ AVIATION... CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM. PATCHY FOG AT TAF SITES KBVO/KXNA/KFYV TO MIX AWAY BY 15Z. VFR ALL SITES UNTIL PATCHY FOG RETURNS AGAIN LATE TONIGHT GENERALLY AFTER 06Z WITH POTENTIAL VISIBILITY BELOW 3 MILES KFYV/KXNA. PREV DISCUSSION... /ISSUED 339 AM CDT FRI AUG 23 2013/ DISCUSSION... A STRONG RIDGE OF HIGH PRESSURE ALOFT WILL REMAIN OVER THE AREA THROUGH THE ENTIRE FORECAST PERIOD. THIS WILL LEAD TO AN EXTENDED STRETCH OF HOT WEATHER WITH VERY LITTLE CHANCE OF RAIN. AN ISOLATED SHOWER OR THUNDERSTORM WILL BE POSSIBLE THE NEXT FEW AFTERNOONS...MAINLY OVER THE HIGHER TERRAIN AREAS...BUT AREAL COVERAGE WILL BE MUCH TOO LOW TO MENTION IN THE FORECAST. AFTERNOON TEMPERATURES MAY INCH UP A BIT NEXT WEEK AS LOW LEVEL WINDS LOSE THE EASTERLY COMPONENT THAT WILL BE PRESENT THE NEXT FEW DAYS. STAYED CLOSE TO GUIDANCE TEMPERATURES THE NEXT COUPLE DAYS. && .PRELIMINARY POINT TEMPS/POPS... TUL 73 94 74 94 / 0 10 0 10 FSM 73 95 74 95 / 0 10 0 10 MLC 72 95 73 95 / 10 10 10 10 BVO 69 93 70 93 / 0 10 0 10 FYV 67 91 68 91 / 0 10 0 10 BYV 69 91 70 91 / 0 10 0 10 MKO 71 94 72 94 / 0 10 0 10 MIO 70 92 71 92 / 0 10 0 10 F10 71 95 72 95 / 10 10 10 10 HHW 73 96 74 96 / 10 10 10 10 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...NONE. AR...NONE. && $$ AVIATION...30
AREA FORECAST DISCUSSION
NWS TULSA OK
907 AM CDT FRI AUG 23 2013 .DISCUSSION... UPPER AIR DATA AT 12Z SHOWS COOLER AND MORE MOIST CONDITIONS IN THE MID LVLS COMPARED TO 24 HRS AGO...FROM 700MB UP TO 500MB. IN THE LATE NIGHT AND EARLY MORNING...THIS MID LVL MOISTURE CREATES SOME INSTABILITY DUE TO NOCTURNAL COOLING ABOVE THIS MOIST LAYER. THIS HAS PRODUCED A FEW HIGH BASED SHOWERS AND A LIGHTNING STRIKE OR TWO OVER EASTERN OKLAHOMA. HOWEVER...AS THE DAY CONTINUES THIS MID LEVEL INSTABILITY WANES AND THUS THE SHOWERS SHOULD DISSIPATE BY MIDDAY AS THE HRRR AND LOCAL WRF MODEL SUGGEST. GRIDS HAVE BEEN UPDATED TO ACCOUNT FOR THE SMALL AREA OF PRECIP DOWN OVER EAST CENTRAL OKLAHOMA. LACY && .PREV DISCUSSION... /ISSUED 709 AM CDT FRI AUG 23 2013/ AVIATION... CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM. PATCHY FOG AT TAF SITES KBVO/KXNA/KFYV TO MIX AWAY BY 15Z. VFR ALL SITES UNTIL PATCHY FOG RETURNS AGAIN LATE TONIGHT GENERALLY AFTER 06Z WITH POTENTIAL VISIBILITY BELOW 3 MILES KFYV/KXNA. PREV DISCUSSION... /ISSUED 339 AM CDT FRI AUG 23 2013/ DISCUSSION... A STRONG RIDGE OF HIGH PRESSURE ALOFT WILL REMAIN OVER THE AREA THROUGH THE ENTIRE FORECAST PERIOD. THIS WILL LEAD TO AN EXTENDED STRETCH OF HOT WEATHER WITH VERY LITTLE CHANCE OF RAIN. AN ISOLATED SHOWER OR THUNDERSTORM WILL BE POSSIBLE THE NEXT FEW AFTERNOONS...MAINLY OVER THE HIGHER TERRAIN AREAS...BUT AREAL COVERAGE WILL BE MUCH TOO LOW TO MENTION IN THE FORECAST. AFTERNOON TEMPERATURES MAY INCH UP A BIT NEXT WEEK AS LOW LEVEL WINDS LOSE THE EASTERLY COMPONENT THAT WILL BE PRESENT THE NEXT FEW DAYS. STAYED CLOSE TO GUIDANCE TEMPERATURES THE NEXT COUPLE DAYS. && .PRELIMINARY POINT TEMPS/POPS... TUL 94 73 94 74 / 10 0 10 0 FSM 95 73 95 74 / 10 0 10 0 MLC 95 72 95 73 / 10 10 10 10 BVO 93 69 93 70 / 10 0 10 0 FYV 91 67 91 68 / 10 0 10 0 BYV 91 69 91 70 / 10 0 10 0 MKO 94 71 94 72 / 10 0 10 0 MIO 92 70 92 71 / 10 0 10 0 F10 95 71 95 72 / 30 10 10 10 HHW 96 73 96 74 / 10 10 10 10 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...NONE. AR...NONE. && $$ SHORT TERM...30
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
435 PM EDT FRI AUG 23 2013 .SYNOPSIS... A COLD FRONT WILL MOVE INTO THE REGION TONIGHT...TRIGGERING SHOWERS AND THUNDERSTORMS BEFORE USHERING IN DRIER WEATHER FOR THE WEEKEND. HIGH PRESSURE WILL BUILD BACK IN FOR THE FIRST PART OF THE WEEK...BEGINNING A GRADUAL WARMING TREND. RETURNING SOUTHERLY FLOW WILL GRADUALLY INCREASE MOISTURE ACROSS THE REGION...INCREASING CHANCES FOR SHOWERS AND THUNDERSTORMS EACH AFTERNOON. A SERIES OF COLD FRONTS WILL MOVE THROUGH THE REGION LATE IN THE WEEK ELEVATING RAIN CHANCES FURTHER. && .NEAR TERM /THROUGH SATURDAY/... AS OF 430 PM...AREA OF CONVECTION IS SHIFTING TO THE WRN CWFA AND DYING OFF EAST OF I-77. HAVE UPDATED AFTERNOON AND EVENING POP TO REFLECT THESE TRENDS. NOW HAVE HIGHEST POP FOLLOWING THE TRACK OF THE CURRENT OUTFLOW BOUNDARY AND SPREADING ACROSS THE UPSTATE INTO NE GA. ALSO HAVE HIGH POP SPREADING SW ACROSS THE NC MTNS AS WELL. POP SIGNIFICANTLY REDUCED OVER THE I-77 CORRIDOR. SVR STORMS REMAIN POSSIBLE AS THE STORMS MOVE INTO AN AREA WITH SIGNIFICANTLY HIGHER DCAPE VALUES. TEMPS FELL SIGNIFICANTLY WITH THE LINE OF TSRA AND HAVE FOLLOWED THESE TRENDS AS WELL...ALTHOUGH NOT AS DRAMATICALLY. AS OF 230 PM EDT FRIDAY...A LINE OF SHOWERS AND THUNDERSTORMS HAS DEVELOPED OVER THE WRN NC FOOTHILLS AND PIEDMONT. THE LINE IS BEING FORCED BY LLVL SFC CONVERGENCE AND DIFFERENTIAL HEATING RESULTING FROM THE APPROACH OF AN H5 SHORT WAVE WHICH THE RAP CURRENTLY HAS LOCATED OVER NE TN AND SW VA. THE DEEP LAYER SHEAR ISN/T STRONG...BUT THE AIRMASS AHEAD OF THE LINE IS QUITE UNSTABLE AND IT ALREADY HAS A WELL ESTABLISHED REAR INFLOW JET PER THE TERMINAL DOPPLER RADAR AT CHARLOTTE. THE NAM AND GFS BOTH STRENGTHEN SFC CONVERGENCE AHEAD OF THE LINE. THEREFORE IT SHOULD CONTINUE TO MOVE TO THE SOUTHEAST AND AT LEAST MAINTAIN ITSELF IF NOT GET STRONGER. BUT IT SHOULD ALSO BUILD TO THE SOUTHWEST...OR NEW STORMS MAY ORIGINATE OVER THE SC MTNS...AS THE LLVL WINDS BACK ACROSS MOST OF THE UPSTATE AND EVEN INTO NE GA OVER THE NEXT COUPLE HOURS. AT THIS RATE MOST LOCATIONS OVER THE FOOTHILLS AND PIEDMONT SHOULD GET INTO THE ACT OVER THE NEXT 4 TO 6 HOURS AND POPS HAVE BEEN RAISED TO LIKELY TO CATEGORICAL FOR THE REST OF THE DAY. DCAPE VALUES ARE HIGH OVER THE UPSTATE...BUT DROP OFF RAPIDLY INTO NORTH CAROLINA. SO AS THE LINE MOVE SOUTHWARD...IT/S TENDENCY TO PRODUCE STRONG OUTFLOW SHOULD INCREASE. STORMS SHOULD DIMINISH FROM NORTH TO SOUTH THIS EVENING. I THINK THERE WILL ENOUGH CONVECTIVE DEBRIS AND MIXING EAST OF THE MTNS TO PREVENT FOG FROM FORMING AGAIN. OVER THE MOUNTAINS WINDS ARE EXPECTED TO DECOUPLE OVERNIGHT AS THE LLVL GRADIENT WINDS WILL BE ORIENTED OUT OF THE NE...ORTHOGONAL TO THE HIGHER NC MTN CHAINS. THEREFORE...THE MTN VALLEYS SHOULD SEE FOG AND STRATUS ONCE AGAIN. COLD AIR DAMMING DEVELOPS FOR SATURDAY. THE MODELS STILL HAVE 1000-2000 SBCAPE VALUES OVER THE SOUTHERN ZONES. I/VE KEPT LOW END CHANCE POPS ALONG THE UPPER SAVANNAH RIVER VALLEY AND OVER THE SOUTHWEST AND CENTRAL NC MTNS. TYPICALLY IN THESE SITUATIONS MOST OF THE DEVELOPMENT IS OVER THE SW MTNS AND ALONG THE EASTERN ESCARPMENT OF THE BLUE RIDGE. CLOUDS MAY DISSIPATE IN THE DRIER AIR OVER THE PIEDMONT AND ALONG THE TN LINE...WITH GENERALLY MOSTLY CLOUDY SKIES EXPECTED ELSEWHERE. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... AT 230 PM EDT FRIDAY...A STRONG UPPER HIGH WILL BE CENTERED OVER MO ON SATURDAY NIGHT....WHILE A POSITIVELY TILTED UPPER TROUGH WILL BE JUST OFF THE EAST COAST. THIS TROUGH MOVES FARTHER OFF THE EAST COAST ON SUNDAY...WHILE THE UPPER RIDGE REMAINS CENTERED OVER MO. ON MONDAY THE UPPER RIDGE RETROGRESSES INTO KS. A COLD FRONT TO OUR SOUTH WILL DRIFT FARTHER SOUTH ACROSS FL SATURDAY NIGHT AND SUNDAY...WHILE DRIER AIR AND HIGH PRESSURE SPREAD ACROSS THE CAROLINAS AND GA FROM THE NE. MODEL TIME HEIGHTS SHOW A THINNING...LINGERING LAYER OF MOISTURE AT AROUND 850 MB BEHIND THE FRONT. WITH JUST A WEAK EASTERLY UPSLOPE FLOW DEVELOPING AS WINDS VEER IN THE LOW LEVELS...ONLY VERY SMALL POPS WILL BE CARRIED SUNDAY EVENING AND LATE MONDAY. TEMPERATURES WILL RUN BELOW NORMAL THROUGH THE PERIOD...WITH A SLIGHT WARMING TREND ON MONDAY AS HEIGHTS RISE ALOFT WITH THE PROGRESSION OF THE ATLANTIC TROUGH. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... AS OF 200 PM EDT FRIDAY...OVERALL A MUCH DRIER PATTERN FOR THE EXTENDED THAN WHAT WE HAVE SEEN IN THE PAST FEW WEEKS. AN UPPER RIDGE WILL BE FIRMLY ENTRENCHED OVER THE CENTRAL PLAINS BY MONDAY NIGHT WHILE A SURFACE RIDGE WILL SHIFT SOUTHEASTWARD TOWARDS THE ATLANTIC TO TAKE ON BERMUDA HIGH CHARACTERISTICS. THIS WILL SET UP A WEAK SOUTHEASTERLY FLOW REGIME AT THE SURFACE...AND BY WEDNESDAY A HIGH IN THE NORTHEAST WILL ALLOW A WEAK WEDGE TO BUILD IN OVER THE APPALACHIANS AND ADVECT IN MODERATELY DRIER AIR. ANY CONVECTION WILL FOLLOW A DIURNAL PATTERN...AND THEN WILL BE LIMITED MAINLY TO AREAS OF UPSLOPE FLOW. AN EXPANDING SURFACE HIGH OVER THE GREAT LAKES WILL PUSH MULTIPLE FRONTAL BOUNDARIES SOUTHWARD THROUGH THE CWA BY THE END OF THE WEEK...INCREASING RAIN CHANCES ONCE AGAIN. RISING HEIGHTS DUE TO THE UPPER LEVEL RIDGE WILL ALLOW HIGH TEMPERATURES TO MODERATE BACK TO NORMAL LEVELS...IN THE MID TO HIGH 80S...FOR MOST OF NEXT WEEK. && .AVIATION /21Z FRIDAY THROUGH WEDNESDAY/... AT KCLT...THE LINE OF THUNDERSTORMS WEAKENED AND SPLIT THE AIRFIELD. CHC FOR ADDITIONAL ACTIVITY NEAR THE AIRPORT IS LOW THIS EVENING... SO WILL REMOVE MENTION...BUT WATCH FOR NEEDED AMD. WINDS SHUD STAY LIGHT FROM THE NORTH INTO THE EVENING. IN FACT...SHOULD ONLY SEE SCT LOW VFR CLOUDS UNLESS MORE CELLS DEVELOP. LATER TONIGHT AN MVFR STRATO-CU DECK MAY MOVE IN AS THE TRUE SFC OLD FRONT ARRIVES. THE RAP AND OUR LOCAL WRF ARW DO THIS AND I/VE ADDED A PERIOD OF MVFR CIGS FROM 09-14 UTC TONIGHT AND TMRW. WINDS WILL VEER FROM NW TO NE AS THE FRONT MOVES THROUGH. ELSEWHERE...A LINE OF THUNDERSTORMS WILL DROP SOUTHEAST AND SHUD AFFECT KGSP/KGMU THIS AFTERNOON AND POSSIBLY KAVL/KAND. KHKY LOOKS TO BE OUT OF DANGER...BUT AN ADDITIONAL CELL COULD DEVELOP LATER. WINDS WILL GO NORTH BEHIND THE GUST FRONT ASSOCIATED WITH THE LINE OF STORMS. THEN LOW VFR CLEARS OUT UNTIL LATER TONIGHT. LATER TONIGHT MVFR CIGS WILL DEVELOP OVER NC...BUT THEY MAY NOT MAKE IT INTO THE UPSTATE. THEREFORE NO MVFR CIGS WERE CARRIED AT THE SOUTH CAROLINA TAF SITES. AT KAVL THE WINDS SHOULD BE COME LIGHT LATE TONIGHT AS THE FRONT IS MOVING IN FROM THE NE. THIS WILL SUPPORT ANOTHER NIGHT WITH STRATUS AND FOG. WINDS WILL BECOME RATHER BRISK OUT OF THE NORTHEAST AFTER SUNRISE. I WOULDN/T BE SURPRISED TO SEE SOME GUSTS UP TO 20 KTS OVER THE UPSTATE AND AT KCLT. OUTLOOK...A DRIER PATTERN IS EXPECTED AS HIGH PRESSURE GRADUALLY BUILDS IN FROM THE NORTH OVER THE WEEKEND. CONFIDENCE TABLE... 20-02Z 02-08Z 08-14Z 14-20Z KCLT HIGH 100% HIGH 100% HIGH 81% HIGH 95% KGSP HIGH 100% HIGH 91% HIGH 100% HIGH 100% KAVL HIGH 100% MED 67% LOW 56% MED 67% KHKY HIGH 100% HIGH 80% LOW 52% HIGH 95% KGMU HIGH 100% HIGH 91% HIGH 95% HIGH 100% KAND HIGH 100% HIGH 100% HIGH 100% HIGH 100% THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE) WWW.WEATHER.GOV/GSP/AVIATION_TABLES && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...VISIN NEAR TERM...MCAVOY/RWH SHORT TERM...JAT LONG TERM...VISIN AVIATION...MCAVOY/RWH
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
229 PM EDT FRI AUG 23 2013 .SYNOPSIS... A COLD FRONT WILL MOVE INTO THE REGION TONIGHT...TRIGGERING SHOWERS AND THUNDERSTORMS BEFORE USHERING IN DRIER WEATHER FOR THE WEEKEND. HIGH PRESSURE WILL BUILD BACK IN FOR THE FIRST PART OF THE WEEK...BEGINNING A GRADUAL WARMING TREND. RETURNING SOUTHERLY FLOW WILL GRADUALLY INCREASE MOISTURE ACROSS THE REGION...INCREASING CHANCES FOR SHOWERS AND THUNDERSTORMS EACH AFTERNOON. A SERIES OF COLD FRONTS WILL MOVE THROUGH THE REGION LATE IN THE WEEK ELEVATING RAIN CHANCES FURTHER. && .NEAR TERM /THROUGH SATURDAY/... AS OF 230 PM EDT FRIDAY...A LINE OF SHOWERS AND THUNDERSTORMS HAS DEVELOPED OVER THE WRN NC FOOTHILLS AND PIEDMONT. THE LINE IS BEING FORCED BY LLVL SFC CONVERGENCE AND DIFFERENTIAL HEATING RESULTING FROM THE APPROACH OF AN H5 SHORT WAVE WHICH THE RAP CURRENTLY HAS LOCATED OVER NE TN AND SW VA. THE DEEP LAYER SHEAR ISN/T STRONG...BUT THE AIRMASS AHEAD OF THE LINE IS QUITE UNSTABLE AND IT ALREADY HAS A WELL ESTABLISHED REAR INFLOW JET PER THE TERMINAL DOPPLER RADAR AT CHARLOTTE. THE NAM AND GFS BOTH STRENGTHEN SFC CONVERGENCE AHEAD OF THE LINE. THEREFORE IT SHOULD CONTINUE TO MOVE TO THE SOUTHEAST AND AT LEAST MAINTAIN ITSELF IF NOT GET STRONGER. BUT IT SHOULD ALSO BUILD TO THE SOUTHWEST...OR NEW STORMS MAY ORIGINATE OVER THE SC MTNS...AS THE LLVL WINDS BACK ACROSS MOST OF THE UPSTATE AND EVEN INTO NE GA OVER THE NEXT COUPLE HOURS. AT THIS RATE MOST LOCATIONS OVER THE FOOTHILLS AND PIEDMONT SHOULD GET INTO THE ACT OVER THE NEXT 4 TO 6 HOURS AND POPS HAVE BEEN RAISED TO LIKELY TO CATEGORICAL FOR THE REST OF THE DAY. DCAPE VALUES ARE HIGH OVER THE UPSTATE...BUT DROP OFF RAPIDLY INTO NORTH CAROLINA. SO AS THE LINE MOVE SOUTHWARD...IT/S TENDENCY TO PRODUCE STRONG OUTFLOW SHOULD INCREASE. STORMS SHOULD DIMINISH FROM NORTH TO SOUTH THIS EVENING. I THINK THERE WILL ENOUGH CONVECTIVE DEBRIS AND MIXING EAST OF THE MTNS TO PREVENT FOG FROM FORMING AGAIN. OVER THE MOUNTAINS WINDS ARE EXPECTED TO DECOUPLE OVERNIGHT AS THE LLVL GRADIENT WINDS WILL BE ORIENTED OUT OF THE NE...ORTHOGONAL TO THE HIGHER NC MTN CHAINS. THEREFORE...THE MTN VALLEYS SHOULD SEE FOG AND STRATUS ONCE AGAIN. COLD AIR DAMMING DEVELOPS FOR SATURDAY. THE MODELS STILL HAVE 1000-2000 SBCAPE VALUES OVER THE SOUTHERN ZONES. I/VE KEPT LOW END CHANCE POPS ALONG THE UPPER SAVANNAH RIVER VALLEY AND OVER THE SOUTHWEST AND CENTRAL NC MTNS. TYPICALLY IN THESE SITUATIONS MOST OF THE DEVELOPMENT IS OVER THE SW MTNS AND ALONG THE EASTERN ESCARPMENT OF THE BLUE RIDGE. CLOUDS MAY DISSIPATE IN THE DRIER AIR OVER THE PIEDMONT AND ALONG THE TN LINE...WITH GENERALLY MOSTLY CLOUDY SKIES EXPECTED ELSEWHERE. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... AT 230 PM EDT FRIDAY...A STRONG UPPER HIGH WILL BE CENTERED OVER MO ON SATURDAY NIGHT....WHILE A POSITIVELY TILTED UPPER TROUGH WILL BE JUST OFF THE EAST COAST. THIS TROUGH MOVES FARTHER OFF THE EAST COAST ON SUNDAY...WHILE THE UPPER RIDGE REMAINS CENTERED OVER MO. ON MONDAY THE UPPER RIDGE RETROGRESSES INTO KS. A COLD FRONT TO OUR SOUTH WILL DRIFT FARTHER SOUTH ACROSS FL SATURDAY NIGHT AND SUNDAY...WHILE DRIER AIR AND HIGH PRESSURE SPREAD ACROSS THE CAROLINAS AND GA FROM THE NE. MODEL TIME HEIGHTS SHOW A THINNING...LINGERING LAYER OF MOISTURE AT AROUND 850 MB BEHIND THE FRONT. WITH JUST A WEAK EASTERLY UPSLOPE FLOW DEVELOPING AS WIDNS VEER IN THE LOW LEVELS...ONLY VERY SMALL POPS WILL BE CARRIED LATE MONDAY. TEMPERATURES WILL RUN BELOW NORMAL THROUGH THE PERIOD...WITH A SLIGHT WARMING TREND ON MONDAY AS HEIGHTS RISE ALOFT WITH THE PROGRESSION OF THE ATLANTIC TROUGH. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... AS OF 200 PM EDT FRIDAY...OVERALL A MUCH DRIER PATTERN FOR THE EXTENDED THAN WHAT WE HAVE SEEN IN THE PAST FEW WEEKS. AN UPPER RIDGE WILL BE FIRMLY ENTRENCHED OVER THE CENTRAL PLAINS BY MONDAY NIGHT WHILE A SURFACE RIDGE WILL SHIFT SOUTHEASTWARD TOWARDS THE ATLANTIC TO TAKE ON BERMUDA HIGH CHARACTERISTICS. THIS WILL SET UP A WEAK SOUTHEASTERLY FLOW REGIME AT THE SURFACE...AND BY WEDNESDAY A HIGH IN THE NORTHEAST WILL ALLOW A WEAK WEDGE TO BUILD IN OVER THE APPALACHIANS AND ADVECT IN MODERATELY DRIER AIR. ANY CONVECTION WILL FOLLOW A DIURNAL PATTERN...AND THEN WILL BE LIMITED MAINLY TO AREAS OF UPSLOPE FLOW. AN EXPANDING SURFACE HIGH OVER THE GREAT LAKES WILL PUSH MULTIPLE FRONTAL BOUNDARIES SOUTHWARD THROUGH THE CWA BY THE END OF THE WEEK...INCREASING RAIN CHANCES ONCE AGAIN. RISING HEIGHTS DUE TO THE UPPER LEVEL RIDGE WILL ALLOW HIGH TEMPERATURES TO MODERATE BACK TO NORMAL LEVELS...IN THE MID TO HIGH 80S...FOR MOST OF NEXT WEEK. && .AVIATION /19Z FRIDAY THROUGH WEDNESDAY/... AT KCLT...A LINE OF THUNDERSTORMS IS ORGANIZING 40 TO 50 MILES NORTHWEST OF THE AIRFIELD. IT SHOULD CONTINUE MOVING SOUTHEAST AND WILL LIKELY ACCELERATE A LITTLE AS IT DOES. TEMPO THUNDER HAS BEEN MOVED UP AN HOUR...FROM 19-22 UTC. STORMS ARE SHOWING 30-35KT INBOUNDS ON TDWR. THE LINE SHOULD STRENGTHEN SOME AS IT APPROACHES AND I/VE ADDED A PERIOD OF 35 KT GUSTS TO THE TAF. I WENT VARIABLE...THOUGH THE STRONGEST WINDS ARE LIKELY TO BE ORIENTED OUT OF THE NORTH. SCT SHRA AND A FEW TSTMS WILL PERSIST INTO THE LATE EVENING HOURS. LATER TONIGHT AN MVFR STRATO-CU DECK MAY MOVE IN AS THE TRUE SFC OLD FRONT ARRIVES. THE RAP AND OUR LOCAL WRF ARW DO THIS AND I/VE ADDED A PERIOD OF MVFR CIGS FROM 09-14 UTC TONIGHT AND TWRW. WINDS WILL VEER FROM NW TO NE AS THE FRONT MOVES THROUGH. ELSEWHERE...A LINE OF THUNDERSTORMS WILL DROP SOUTHEAST ACROSS THE NC AND SC PIEDMONT THIS AFTERNOON AND EVENING. THE QUESTION IS HOW FAR TO THE SOUTHWEST THE LINE WILL BUILD. THE MODELS HAVE GOOD CONVERGENCE WELL INTO THE UPSTATE...SO I THINK THE LINE WILL BUILD TO THE SOUTHWEST AND I/VE ADDED TEMPO THUNDER IN AT KGMU/KGSP STARTING AT 20 UTC. THE LINE IS PRACTICALLY ON TOP OF HKY AND THEY HAVE A TEMPO FOR THE NEXT COUPLE HOURS. I/M NOT AS CONFIDENT OF KAND AND TEMPO WAS LEFT OUT OF THAT SITE. KAVL WILL PROBABLY SEE SOMETHING SO THEY GOT A TEMPO AS WELL. LATER TONIGHT MVFR CIGS WILL DEVELOP OVER NC...BUT THEY MAY NOT MAKE IT INTO THE UPSTATE. THEREFORE NO MVFR CIGS WERE CARRIED AT THE SOUTH CAROLINA TAF SITES. AT KAVL THE WINDS SHOULD BE COME LIGHT LATE TONIGHT AS THE FRONT IS MOVING IN FROM THE NE. THIS WILL SUPPORT ANOTHER NIGHT WITH STRATUS AND FOG. WINDS WILL BECOME RATHER BRISK OUT OF THE NORTHEAST AFTER SUNRISE. I WOULDN/T BE SURPRISED TO SEE SOME GUSTS UP TO 20 KTS OVER THE UPSTATE AND AT KCLT. OUTLOOK...A DRIER PATTERN IS EXPECTED AS HIGH PRESSURE GRADUALLY BUILDS IN FROM THE NORTH OVER THE WEEKEND. CONFIDENCE TABLE... 18-24Z 00-06Z 06-12Z 12-18Z KCLT HIGH 100% HIGH 100% HIGH 85% HIGH 85% KGSP HIGH 100% HIGH 100% HIGH 80% HIGH 97% KAVL HIGH 100% MED 77% LOW 51% LOW 56% KHKY HIGH 100% HIGH 94% LOW 42% HIGH 81% KGMU HIGH 100% HIGH 100% HIGH 83% HIGH 100% KAND HIGH 100% HIGH 100% HIGH 100% HIGH 100% THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE) WWW.WEATHER.GOV/GSP/AVIATION_TABLES && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...VISIN NEAR TERM...MCAVOY SHORT TERM...JAT LONG TERM...VISIN AVIATION...MCAVOY
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
201 PM EDT FRI AUG 23 2013 .SYNOPSIS... A COLD FRONT WILL MOVE INTO THE REGION TONIGHT...TRIGGERING SHOWERS AND THUNDERSTORMS BEFORE USHERING IN DRIER WEATHER FOR THE WEEKEND. HIGH PRESSURE WILL BUILD BACK IN FOR THE FIRST PART OF THE WEEK...BEGINNING A GRADUAL WARMING TREND. RETURNING SOUTHERLY FLOW WILL GRADUALLY INCREASE MOISTURE ACROSS THE REGION...INCREASING CHANCES FOR SHOWERS AND THUNDERSTORMS EACH AFTERNOON. A SERIES OF COLD FRONTS WILL MOVE THROUGH THE REGION LATE IN THE WEEK ELEVATING RAIN CHANCES FURTHER. && .NEAR TERM /THROUGH TONIGHT/... AS OF 950 AM EDT FRIDAY...FOG AND STRATUS CONTINUES TO BURN OFF THIS MORNING...THOUGH IT IS LINGERING ACROSS THE NC MTN VALLEYS AND OVER A FEW LOW SPOTS OUT ACROSS THE FOOTHILLS AND PIEDMONT. FORECAST REASONING FOR THE AFTERNOON HOURS HASN/T CHANGED MUCH. A SHORT WAVE WILL CROSS THE REGION BETWEEN 21-00 UTC. CAPE VALUES WILL BE FAIRLY HIGH...THOUGH LAPSE RATES WILL BE WEAK. ALSO...THE SPC FORECAST MESOANALYSIS FOR THE FORECAST AREA HAS EFFECTIVE BULK SHEAR VALUES UNDER 20 KTS THROUGH THE MID AFTN HOURS. THE VARIOUS CONVECTIVE ALLOWING MODELS DON/T HAVE MUCH OVER OUR AREA...FAVORING MORE VIGOROUS DEVELOPMENT OVER ERN NC AND SRN VA WHERE THE DEEP LAYER SHEAR IS STRONGER. CONSIDERING ALL THIS I AM NOT GOING TO UP POPS INTO THE LIKELY RANGE THIS AFTN. I THINK WE WILL SEE DECENT COVERAGE...BUT I DON/T THINK THE FORCING SUPPORTS ANY ESCALATION OF WHAT WE HAVE IN THERE ALREADY. AS OF 700 AM EDT...THE FOG FORECAST REMAINS CHALLENGING THIS MORNING...WITH MANY LOCATIONS THAT HAVE WET GROUND SEEING VSBY QUITE VARIABLE AND DIPPING INTO DENSE FOG RANGE...ESPECIALLY THE FOOTHILLS AND MTN VALLEYS. HOWEVER...MID AND HIGH CLOUDS ARE THICKENING ALOFT WHICH COULD PUT THE BREAKS ON MORE WIDESPREAD FOG DEVELOPMENT...AND MUCH OF THE 1/4SM VSBY HAS BEEN SHALLOWER GROUND FOG. AN SPS HAS BEEN ISSUED FOR MTNS/FOOTHILLS...AND ADDITIONAL FOG/PATCHY DENSE WORDING HAS BEEN ADDED TO THE FORECAST. OTHERWISE...THE FORECAST REMAINS ON TRACK WITH WATER VAPOR IMAGERY SHOWING A SHORTWAVE MOVING SE FROM THE OH VALLEY EARLY THIS MORNING...ATOP AN ASSOCIATED SFC COLD FRONT. THE BOUNDARY WILL MOVE INTO THE FORECAST AREA THROUGH THE DAY...WITH UPPER JET DIVERGENCE GRADUALLY SHARPENING UP OVERHEAD...ALONG WITH IMPROVING LOW LEVEL CONVERGENCE ALONG THE FRONTAL ZONE. THIS FORCING SHOULD COMBINE WITH SFC BASED INSTABILITY REACHING 2500 TO 3000 J/KG CAPE THIS AFTN ACROSS THE SE HALF OF THE FORECAST AREA. ANTICIPATE FAIRLY DECENT SCATTERED COVERAGE THROUGHOUT THIS AFTN...BUT WITH THE BEST CHANCE OF STRONG TO SEVERE THUNDERSTORMS ALONG AND SE OF THE INTERSTATE 85 CORRIDOR. WIND SHEAR WILL BE FAIRLY LIMITED UP THE COLUMN...BUT WITH JUST ENOUGH DIRECTIONAL/SPEED SHEAR FOR WEAK MULTI CELL DEVELOPMENT IN THE DEEP LAYER FORCING. WILL HIGHLIGHT THE POTENTIAL IN THE HWO. TEMPS AHEAD OF THE FRONTAL ZONE THIS AFTN WILL REACH MAXES AT OR SLIGHTLY ABOVE CLIMATE AVERAGES. THE BOUNDARY WILL SETTLE S OF THE FORECAST AREA TONIGHT. DEEP LAYER N TO NW FLOW WILL SET UP BEHIND THE FRONT OVERNIGHT...WITH DRYING AT MID AND UPPER LEVELS. HOWEVER...SOME BL TO 850 MB MOISTURE WILL LIKELY LINGER IN THE NRLY FLOW FOR SOME ATTENDANT CLOUDS TO DEVELOP AND KEEP MINS ABOVE NORMAL VALUES. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 200 AM EDT FRIDAY...AS UPPER TROF CONTINUES TO MOVE OFF THE EAST COAST...SURFACE COLD FRONT WILL HAVE PUSHED INTO THE EXTREME SOUTHEAST NEAR THE I10 CORRIDOR. SFC HIGH PRESSURE WILL BEGIN TO BUILD IN ACROSS THE GREAT LAKES REGION BEHIND THE EXITING UPPER TROF. DUE TO THE WEAK NATURE OF THE BOUNDARY THAT PASSED THROUGH THE PREVIOUS DAY...SFC DEWPOINTS WILL STILL BE IN THE UPPER 60S ACROSS THE NC/SC PIEDMONT REGIONS THUS KEEPING POTENTIAL FOR SOME SCATTERED SHOWERS ELEVATED DURING THE DAY ON SATURDAY. FURTHER WEST ACROSS THE MOUNTAINS...EVEN THOUGH MOISTURE IS SLIGHTLY LOWER...DYNAMIC UPSLOPE FORCING COULD PROVIDE ENOUGH LIFT FOR SOME CONVECTION INTO THE AFTERNOONS HOURS. THUS FOR SATURDAY...KEPT SLIGHT CHANCE POPS ACROSS THE PIEDMONT REGIONS AS DIURNAL HEATING WILL COMBINE WITH ABOVE MENTIONED UPPER 60S DEWPOINTS TO CREATE AT LEAST SOME SURFACE BASED INSTABILITY...THEREFORE SHOWERS COULD NOT BE RULED OUT. AS FOR THE HIGH TERRAIN...HIGHLIGHTED SLIGHTLY HIGHER CHANCE POPS DUE TO UPSLOPE COMPONENT. TAPERED POPS BACK DURING THE OVERNIGHT HOURS ACROSS THE ENTIRE REGION. TEMPERATURES ON SATURDAY LOOK TO BE A FEW DEGREES BELOW NORMAL. SUNDAY IS LOOKING LIKE A RATHER NICE DAY ACROSS THE REGION. SFC HIGH PRESSURE WILL SLOWLY DRIFT SOUTHEAST DURING THE EARLY MORNING HOURS...THUS STRENGTHENING NORTHEAST FLOW ALLOWING A WEAK WEDGE TO DOMINATE THE REGION. AS DRIER AIR IS ADVECTED IN...MODEL GUIDANCE REMAINS IN GOOD AGREEMENT WITH REGARDS TO LACK OF INSTABILITY AS MOISTURE AXIS SHIFTS SOUTH. THEREFORE KEPT POPS OUT OF THE FORECAST FOR SUNDAY ACROSS THE ENTIRE REGION. ALTHOUGH TEMPERATURES WILL REMAIN IN THE LOWER 80S ON SUNDAY...IT SHOULD FEEL MORE PLEASANT OUTSIDE AS LOWER DEWPOINTS REDUCE HUMIDITY. && .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 200 PM EDT FRIDAY...OVERALL A MUCH DRIER PATTERN FOR THE EXTENDED THAN WHAT WE HAVE SEEN IN THE PAST FEW WEEKS. AN UPPER RIDGE WILL BE FIRMLY ENTRENCHED OVER THE CENTRAL PLAINS BY MONDAY NIGHT WHILE A SURFACE RIDGE WILL SHIFT SOUTHEASTWARD TOWARDS THE ATLANTIC TO TAKE ON BERMUDA HIGH CHARACTERISTICS. THIS WILL SET UP A WEAK SOUTHEASTERLY FLOW REGIME AT THE SURFACE...AND BY WEDNESDAY A HIGH IN THE NORTHEAST WILL ALLOW A WEAK WEDGE TO BUILD IN OVER THE APPALACHIANS AND ADVECT IN MODERATELY DRIER AIR. ANY CONVECTION WILL FOLLOW A DIURNAL PATTERN...AND THEN WILL BE LIMITED MAINLY TO AREAS OF UPSLOPE FLOW. AN EXPANDING SURFACE HIGH OVER THE GREAT LAKES WILL PUSH MULTIPLE FRONTAL BOUNDARIES SOUTHWARD THROUGH THE CWA BY THE END OF THE WEEK...INCREASING RAIN CHANCES ONCE AGAIN. RISING HEIGHTS DUE TO THE UPPER LEVEL RIDGE WILL ALLOW HIGH TEMPERATURES TO MODERATE BACK TO NORMAL LEVELS...IN THE MID TO HIGH 80S...FOR MOST OF NEXT WEEK. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... AT KCLT...A LINE OF THUNDERSTORMS IS ORGANIZING 40 TO 50 MILES NORTHWEST OF THE AIRFIELD. IT SHOULD CONTINUE MOVING SOUTHEAST AND WILL LIKELY ACCELERATE A LITTLE AS IT DOES. TEMPO THUNDER HAS BEEN MOVED UP AN HOUR...FROM 19-22 UTC. STORMS ARE SHOWING 30-35KT INBOUNDS ON TDWR. THE LINE SHOULD STRENGTHEN SOME AS IT APPROACHES AND I/VE ADDED A PERIOD OF 35 KT GUSTS TO THE TAF. I WENT VARIABLE...THOUGH THE STRONGEST WINDS ARE LIKELY TO BE ORIENTED OUT OF THE NORTH. SCT SHRA AND A FEW TSTMS WILL PERSIST INTO THE LATE EVENING HOURS. LATER TONIGHT AN MVFR STRATO-CU DECK MAY MOVE IN AS THE TRUE SFC OLD FRONT ARRIVES. THE RAP AND OUR LOCAL WRF ARW DO THIS AND I/VE ADDED A PERIOD OF MVFR CIGS FROM 09-14 UTC TONIGHT AND TWRW. WINDS WILL VEER FROM NW TO NE AS THE FRONT MOVES THROUGH. ELSEWHERE...A LINE OF THUNDERSTORMS WILL DROP SOUTHEAST ACROSS THE NC AND SC PIEDMONT THIS AFTERNOON AND EVENING. THE QUESTION IS HOW FAR TO THE SOUTHWEST THE LINE WILL BUILD. THE MODELS HAVE GOOD CONVERGENCE WELL INTO THE UPSTATE...SO I THINK THE LINE WILL BUILD TO THE SOUTHWEST AND I/VE ADDED TEMPO THUNDER IN AT KGMU/KGSP STARTING AT 20 UTC. THE LINE IS PRACTICALLY ON TOP OF HKY AND THEY HAVE A TEMPO FOR THE NEXT COUPLE HOURS. I/M NOT AS CONFIDENT OF KAND AND TEMPO WAS LEFT OUT OF THAT SITE. KAVL WILL PROBABLY SEE SOMETHING SO THEY GOT A TEMPO AS WELL. LATER TONIGHT MVFR CIGS WILL DEVELOP OVER NC...BUT THEY MAY NOT MAKE IT INTO THE UPSTATE. THEREFORE NO MVFR CIGS WERE CARRIED AT THE SOUTH CAROLINA TAF SITES. AT KAVL THE WINDS SHOULD BE COME LIGHT LATE TONIGHT AS THE FRONT IS MOVING IN FROM THE NE. THIS WILL SUPPORT ANOTHER NIGHT WITH STRATUS AND FOG. WINDS WILL BECOME RATHER BRISK OUT OF THE NORTHEAST AFTER SUNRISE. I WOULDN/T BE SURPRISED TO SEE SOME GUSTS UP TO 20 KTS OVER THE UPSTATE AND AT KCLT. OUTLOOK...A DRIER PATTERN IS EXPECTED AS HIGH PRESSURE GRADUALLY BUILDS IN FROM THE NORTH OVER THE WEEKEND. CONFIDENCE TABLE... 18-24Z 00-06Z 06-12Z 12-18Z KCLT HIGH 100% HIGH 100% HIGH 85% HIGH 85% KGSP HIGH 100% HIGH 100% HIGH 80% HIGH 97% KAVL HIGH 100% MED 77% LOW 51% LOW 56% KHKY HIGH 100% HIGH 94% LOW 42% HIGH 81% KGMU HIGH 100% HIGH 100% HIGH 83% HIGH 100% KAND HIGH 100% HIGH 100% HIGH 100% HIGH 100% THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE) WWW.WEATHER.GOV/GSP/AVIATION_TABLES && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...CDG NEAR TERM...HG/MCAVOY SHORT TERM...CDG LONG TERM...VISIN AVIATION...MCAVOY
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
1004 PM CDT SAT AUG 24 2013 .UPDATE... POPS AND WEATHER GRIDS FOR TONIGHT AND SUNDAY. && .DISCUSSION... EQUIPMENT ISSUE OF NOTE...THE GALVESTON TEMPERATURE IS TOO COOL. TECHNICIANS WILL CHECK OUT THE EQUIPMENT SOMETIME DURING THE NEXT 24 TO 48 HOURS. 00Z ANALYSIS AND MODEL FORECASTS PLACE THE EASTERLY WAVE OVER THE NORTHERN GULF ALONG THE LA COAST INTO THE CENTRAL GULF OF MEXICO. BOTH THE RAP AND NAM12 700 TO 300 MEAN LAYER FORECAST SHOWS THAT A SMALLER LOW PRESSURE TROUGH WILL APPROACH THE UPPER TEXAS COAST OVERNIGHT TONIGHT WITH THE MAIN WAVE THEN MOVING TO ALONG THE COAST DURING THE MID MORNING SUNDAY. BOTH MODELS KEEP THE BEST LAYER MOISTURE AND LIFT ALONG THE INTERSTATE 10 CORRIDOR SOUTH DURING THE MIDDAY AND AFTERNOON PERIOD. THE RIDGE TO THE NORTH MAY BE TOO MUCH FOR THE WAVE TO OVERCOME. EXPECT THE MAIN BULK OF THE RAIN CHANCES WILL OCCUR ALONG AND EAST OF THE WAVE AXIS...AND THERE MAY WELL BE A FAIRLY BIG DISCONTINUITY BETWEEN NO TO ISOLATED COVERAGE AND BE BULK OF THE ACTIVITY. FOR THAT REASON WILL ADJUST THE POPS DOWNWARD OVER THE INLAND AREAS TONIGHT AND FROM THE INTERSTATE 10 CORRIDOR NORTHWARD ON SUNDAY. ADJUSTED THE POPS SLIGHTLY DOWNWARD ELSEWHERE AS WELL BOTH PERIODS. 40 && .PREV DISCUSSION... /ISSUED 642 PM CDT SAT AUG 24 2013/ DISCUSSION... 00Z TAF DISCUSSION IN AVIATION SECTION. AVIATION... KCLL/KUTS/KCXO...OVER SHOULD HAVE VFR CIGS WITH MAYBE AN HOUR OR SO OF 5SM AT KCXO IN THE MORNING BUT WILL NOT MENTION IN TAF. CONVECTION WILL BE MAIN ISSUE TOMORROW AS TROPICAL WAVE MOVES INLAND SLOWLY. MAY SEE A FEW SHOWERS A KCXO BUT THINK MAJORITY OF CONVECTION STAYS SOUTH OF THESE TERMINALS. KIAH/KHOU/KSGR...EXPECT VFR CIGS TONIGHT BUT INCREASING CLOUDS THROUGH THE MORNING. MAIN ISSUE WILL BE THE ONSET OF CONVECTION WITH TROPICAL WAVE MOVING INLAND. TROPICAL MOISTURE MAY BE SLOW TO MOVE INLAND SO THINK KIAH WILL BE ON EDGE OF CONVECTION. WILL MENTION VCSH FOR ALL TAFS STARTING EARLIER IN THE DAY FOR KHOU/KSGR AND IN THE AFTERNOON FOR KIAH. WILL NEED TO EVALUATE VCTS FOR KHOU/KSGR FOR 17Z-20Z TIME FRAME FOR 06Z TAFS BASED ON 00Z MODEL RUNS. RIGHT NOW MORE CONFIDENT IN TS FOR KHOU/KSGR THAN KIAH. THINK 00Z MODEL RUNS WILL GIVE BETTER IDEA. ALSO INCREASED WIND FOR AFTERNOON AS PRESSURE GRADIENT TIGHTENS. KLBX/KGLS...MAIN ISSUE WILL BE SHRA DEVELOPING IN THE MORNING AND MOVING INLAND AS TROPICAL WAVE MOVES INLAND. WILL START VCSH AT 09Z FOR BOTH TERMINALS THEN DEVELOPING VCTS BY 15Z WITH MORE DAYTIME HEATING AND INCREASED TROPICAL MOISTURE. THINK THERE COULD BE A GOOD PERIOD OF SCT TSRA FOR BOTH TERMINALS FROM 15-21Z. WILL HOLD OFF ON TEMPO TSRA AND USE 00Z MODELS TO EVALUATE IF THERE WILL BE A TIME FRAME FOR MORE PRONOUNCED TSRA. 39 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 75 94 75 94 74 / 10 30 20 40 20 HOUSTON (IAH) 77 92 75 91 75 / 10 40 40 50 20 GALVESTON (GLS) 79 87 79 87 80 / 30 50 60 60 30 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ DISCUSSION...40 AVIATION/MARINE...39
AREA FORECAST DISCUSSION
NWS SPOKANE WA
815 AM PDT Fri Aug 23 2013 .SYNOPSIS... A potent storm system will bring scattered showers and thunderstorms through the region today. Unsettled conditions will continue across the Inland Northwest over the weekend and majority of next week as a moist southwest flow pattern remains in place. && .DISCUSSION... Update to the forecast to increase the chances of showers and thunderstorms. Upper low is currently spinning over our area and will eject northward through the day. Shower and thunderstorm coverage will gradually advance northward through the day as well, with clearing skies moving up from Oregon later this afternoon. I will be looking at the potential for stronger thunderstorms this afternoon. Right now the HRRR does show moderately strong storms this afternoon over the north. But the extensive cloud cover would likely limit heating, so that HRRR idea may be overdone. Will address this issue in another hour or 2. RJ && .AVIATION... 12Z TAFS: Scattered showers and embedded thunderstorms will continue to expand across central and eastern WA and north ID this morning as an upper shortwave trof tracks northeast from the Cascades. Primarily VFR conditions are expected, though brief MVFR conditions and gusty winds are possible in heavy showers/storms. As morning transitions to afternoon the showers/thunderstorm threat is expected to translate northward, with the west and southern TAF sites drying out and eventually all TAF sites dry out by late afternoon. However look for breezy conditions, with occasional gusts to 20kts. Winds abate in the 00-06Z time frame. /J. Cote` && .PRELIMINARY POINT TEMPS/POPS... Spokane 81 58 82 60 81 58 / 60 10 10 20 20 20 Coeur d`Alene 81 54 83 57 82 55 / 40 10 10 20 20 20 Pullman 82 52 82 54 81 51 / 30 10 10 20 20 20 Lewiston 88 61 90 62 87 61 / 20 10 10 20 20 20 Colville 83 52 86 55 86 52 / 70 20 10 30 20 30 Sandpoint 80 49 81 51 80 51 / 60 10 10 20 20 20 Kellogg 79 53 83 55 81 54 / 40 10 10 20 20 20 Moses Lake 85 58 83 60 82 57 / 20 10 10 30 20 20 Wenatchee 85 60 82 62 80 59 / 50 10 20 20 20 20 Omak 83 57 84 59 85 57 / 70 10 20 20 20 20 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...Red Flag Warning until 2 PM PDT this afternoon for Northern and Central Idaho Panhandle (Zone 101). WA...Red Flag Warning until 2 PM PDT this afternoon for East Washington Northeast (Zone 686)-East Washington Northern Columbia Basin (Zone 673)-East Washington Okanogan Highlands (Zone 687)-East Washington Palouse and Spokane Area (Zone 674). && $$
AREA FORECAST DISCUSSION
NWS SPOKANE WA
644 AM PDT Fri Aug 23 2013 .SYNOPSIS... A potent storm system will bring scattered showers and thunderstorms through the region today. Unsettled conditions will continue across the Inland Northwest over the weekend and majority of next week as a moist southwest flow pattern remains in place. && .DISCUSSION... Early morning update: a shortwave trough is coming into the Cascades of Washington and Columbia Basin and, combined with a theta-e ridge bent across the northern mountains through the Basin, scattered showers have been on the increase over the past several hours. There have been a few embedded thunderstorms too. The recent short-range RUC and HRRR keep a fair amount of the activity along and north of the I-90 corridor, with more isolated activity across the Palouse southward. I have updated the forecast to reduce the PoPs in that latter locations as well as to slightly delay the increase into the Spokane/C`dA areas. However radar trends do show increasing activity, with "popcorn showers" and thunderstorms expanding across the Moses Lake and Upper Columbia Basin zones, skirting western Spokane county at this hour. While most areas won`t see the day "washed-out", be prepared for isolated to widely scattered showers or thunderstorm. There is a fair amount of clear skies south and east of this region, so the heating of the day and incoming trough should help increase the shower/thunderstorm threat in areas where it is not yet occurring. However the speed of the shortwave trough passage may keep this activity isolated to widely scattered. Yet storms may still be capable of producing abundant lightning with little significant precipitation amounts. So the Red Flag Warning continues. /J. Cote` && .AVIATION... 12Z TAFS: Scattered showers and embedded thunderstorms will continue to expand across central and eastern WA and north ID this morning as an upper shortwave trof tracks northeast from the Cascades. Primarily VFR conditions are expected, though brief MVFR conditions and gusty winds are possible in heavy showers/storms. As morning transitions to afternoon the showers/thunderstorm threat is expected to translate northward, with the west and southern TAF sites drying out and eventually all TAF sites dry out by late afternoon. However look for breezy conditions, with occasional gusts to 20kts. Winds abate in the 00-06Z time frame. /J. Cote` && .PRELIMINARY POINT TEMPS/POPS... Spokane 81 58 82 60 81 58 / 20 10 10 20 20 20 Coeur d`Alene 81 54 83 57 82 55 / 20 10 10 20 20 20 Pullman 82 52 82 54 81 51 / 20 10 10 20 20 20 Lewiston 88 61 90 62 87 61 / 20 10 10 20 20 20 Colville 83 52 86 55 86 52 / 40 10 10 30 20 30 Sandpoint 80 49 81 51 80 51 / 40 20 10 20 20 20 Kellogg 79 53 83 55 81 54 / 20 10 10 20 20 20 Moses Lake 85 58 83 60 82 57 / 30 10 10 30 20 20 Wenatchee 85 60 82 62 80 59 / 40 10 20 20 20 20 Omak 83 57 84 59 85 57 / 40 10 20 20 20 20 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...Red Flag Warning until 2 PM PDT this afternoon for Northern and Central Idaho Panhandle (Zone 101). WA...Red Flag Warning until 2 PM PDT this afternoon for East Washington Northeast (Zone 686)-East Washington Northern Columbia Basin (Zone 673)-East Washington Okanogan Highlands (Zone 687)-East Washington Palouse and Spokane Area (Zone 674). && $$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
600 PM CDT FRI AUG 23 2013 .SHORT TERM...(TONIGHT THROUGH SATURDAY NIGHT) ISSUED AT 307 PM CDT FRI AUG 23 2013 MAIN SHORT TERM CONCERN IS SHOWER/THUNDERSTORM CHANCES. WATER VAPOR/RAP 500MB ANALYSIS THIS AFTERNOON SHOWING A PERSISTENT DEEP TROUGHS OF LOW PRESSURE ALONG THE WEST AND EAST COASTS WHILE AMPLIFYING RIDGE WAS BUDGING SLOWLY FROM THE INTERMOUNTAIN WEST INTO THE CENTRAL CONUS. AT THE SURFACE...HIGH PRESSURE WAS CENTERED OVER THE GREAT LAKES REGION. INCREASING SOUTH/SOUTHEAST FLOW WAS NOTED ACROSS OUR AREA ON THE BACKSIDE OF THE HIGH WITH TEMPERATURES IN THE UPPER 70S TO LOWER 80S. CURRENTLY WATCHING WATER VAPOR CLOSELY GIVEN MONSOONAL FLOW TAP INTO THE INTERMOUNTAIN WEST WITH EMBEDDED SHORTWAVE TROUGH/MCV ACTIVITY. ONE SUCH WAVE WAS NOTED MOVING OUT OF WY INTO SD AT THIS TIME. THIS WAVE IS EXPECTED TO PROPAGATE EASTWARD TO THE AREA LATE TONIGHT INTO SATURDAY AND INTERACT WITH AN APPROACHING WARM FRONT. ALSO OF NOTE WILL BE EASTERN PERIPHERY OF INCREASING ISENTROPIC LIFT AND MOISTURE TRANSPORT IMPINGING ON THE AREA. BOTTOM LINE WILL BE INCREASING MID-LEVEL CLOUD COVER ALONG WITH ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS MAINLY WEST OF THE MISSISSIPPI RIVER AFTER MIDNIGHT... AND THEN ACROSS THE REST OF THE AREA SATURDAY. NAM HAS MLCAPE VALUES IN THE 1000-1500J/KG RANGE ACROSS WESTERN WI INTO SOUTHEAST MN/NORTHEAST IA WITH 1-6KM BULK SHEAR VALUES IN THE 20-25KT RANGE. GIVEN THIS FACT...WILL HAVE TO WATCH FOR AN ISOLATED VIGOROUS STORM WITH HEAVIER DOWNPOUR/SMALL HAIL THREAT. OTHERWISE...LOWS TONIGHT ARE EXPECTED TO BOTTOM OUT IN THE UPPER 50S TO THE MIDDLE 60S WITH HIGHS SATURDAY IN THE 80-85 DEGREE RANGE. APPEARS BULK OF SHOWER/THUNDERSTORM ACTIVITY SHOULD PUSH NORTHEAST OF THE AREA WIT THE PASSAGE OF THE WARM FRONT. HOWEVER...MOISTURE TRANSPORT VECTORS STILL FOCUS ACROSS PORTION OF THE AREA MAINLY NORTH OF I-94 THROUGH THE NIGHT. AS SUCH...KEPT A 20-30 PERCENT PROBABILITY OF SHOWERS/THUNDERSTORMS ACROSS THAT AREA. WITH INCREASING HUMIDITY AND GETTING INTO THE WARM SECTOR...LOWS SATURDAY NIGHT EXPECTED TO BOTTOM OUT IN THE UPPER 60S TO LOWER 70S. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 307 PM CDT FRI AUG 23 2013 MAIN TOPIC OF CONCERN THROUGH THE LONG TERM PERIOD WILL BE INCREASING HEAT WITH BUILDING MID/UPPER LEVEL RIDGE OVER THE CENTRAL CONUS AND UPPER MISSISSIPPI RIVER VALLEY REGION. HOWEVER...MAY SEE A COUPLE WEAK TROUGH PASSAGES WITH SHOWER/THUNDERSTORM CHANCES. AS A RESULT...NOT OVERLY CONFIDENT ON HEAT HAZARD HEADLINE AREA PLACEMENT AT THIS TIME. IT APPEARS AT THIS TIME...THE HIGHEST LIKELIHOOD FOR HEAT HAZARD HEADLINES WOULD BE FROM I-94 AND SOUTH...WHICH IS ENTRENCHED MORE INTO THE RIDGE. AREAS NORTH AND EAST OF THIS WILL BE SUSCEPTIBLE TO THESE WEAK TROUGH PASSAGES AND POTENTIAL FOR THUNDERSTORM COMPLEXES ROLLING THROUGH. IT APPEARS HEAT INDEX CRITERIA FOR HEADLINES //100 DEGREES +// WILL BE MET MONDAY AND TUESDAY AFTERNOONS AND EARLY EVENINGS. AS A RESULT...WILL PROBABLY HOLD OFF ON ANY HEAT HEADLINE ISSUANCE FOR NOW. TEMPERATURE/HEAT DETAILS... ECMWF AND GFS BEGIN TO HEAT THINGS UP ON SUNDAY. GOOD MIXING/SOUTHWEST BREEZE WILL COMBINE WITH 925 TEMPERATURES IN THE 27-29C RANGE FOR HIGHS IN THE 90-95F DEGREE RANGE. GOOD MIXING SHOULD DECREASE HUMIDITY SOMEWHAT WITH HEAT INDICES TOPPING OFF IN THE 95-100 DEGREE RANGE. HIGHER HUMIDITY WITH TEMPERATURES TOPPING OFF IN THE LOWER/MIDDLE 90S MONDAY AND TUESDAY WILL PUSH HEAT INDICES INTO THE 100-105 DEGREE RANGE...ESPECIALLY SOUTHWEST OF I-94. THESE DAYS WILL NEED AT LEAST A HEAT ADVISORY. WEDNESDAY/THURSDAY/FRIDAY LOOKING A BIT MORE UNCERTAIN WITH THE 23.12Z ECMWF/GFS SHOWING COOLING 925MB TEMPERATURES WITH TROUGH PASSAGE THROUGH PARTS OF THE AREA/GREAT LAKES REGION. THIS WOULD KEEP THE AREA BELOW HEAT ADVISORY CRITERIA WITH THE POSSIBLE EXCEPTION OF NORTHEAST IA INTO FAR SOUTHWEST WI WEDNESDAY AFTERNOON. MORE HEAT APPEARS TO BE ON THE WAY FOR LABOR DAY WEEKEND. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING) ISSUED AT 600 PM CDT FRI AUG 23 2013 A WARM FRONT WILL GRADUALLY LIFT NORTHEAST ACROSS THE REGION LATER TONIGHT/EARLY SAT. NOT A BIG SHIFT IN THE WINDS...AND NOT MUCH CONVERGENCE AROUND IT. HOWEVER...MESO MODELS POINT TO SOME LOW LEVEL WARM AIR/ISENTROPIC CONVERGENCE WITH IT...ALTHOUGH NOT A WHOLE LOT OF SATURATION THROUGH THE COLUMN PER BUFKIT SOUNDINGS. SEE SOME SCT-BKN CLOUDS...BUT NOT MUCH IN THE WAY OF PCPN AT THIS TIME. THAT SAID...THE HRRR SUGGESTS A THIN LINE OF SCT-BKN -SHRA COULD TRACK ACROSS KLSE NEAR 12Z. OVERALL...THINK THE BETTER CHANCES FOR KRST/KLSE WILL COME LATER IN THE DAY SAT/SAT NIGHT...AS THE TAF SITES GET UNDER STRONGER SOUTHERLY FLOW. BULK OF THE MOISTURE TRANSPORT SHIFTS NORTH BY THE THEN THOUGH...AS DOES THE STRONGEST THERMODYNAMICS. PLUS...WITH AMPLE LOW LEVEL WARM AIR COMES A CAP...SERVING TO INHIBIT CONVECTION. BEST SHRA/TS WILL LIKELY HOLD NORTH OF KRST/KLSE THROUGH SAT NIGHT AS A RESULT. HIGH PRESSURE EXITS EAST TONIGHT...WITH A TIGHTENING PRESSURE GRADIENT WORKING IN OVERNIGHT. SFC WINDS SHOULD NOT LIGHTEN UP TOO MUCH AS A RESULT...WITH BUFKIT SOUNDINGS INDICATING GOOD STIRRING BY 200 FT. THUS...WINDS WILL BE THE MAIN LIMITING FACTOR TO ANY FOG POTENTIAL. EXPECT HIGHER GUSTS SAT AFTERNOON AS WINDS BEGIN TO MIX. && .CLIMATE... ISSUED AT 307 PM CDT FRI AUG 23 2013 HERE ARE SOME RECORD HIGHS FOR LA CROSSE AND ROCHESTER THROUGH LABOR DAY WEEKEND GIVEN THE UPCOMING INCREASE IN HEAT. FOR MORE CLIMATE INFORMATION...SEE OUR WEBSITE AND THE TOP NEWS STORY ON THE HEAT. LA CROSSE ROCHESTER --------- --------- SUN 8/25 97/1948 97/1948 MON 8/26 96/1991 95/1955 TUE 8/27 95/1973 93/1984 WED 8/28 97/1955 96/1955 THU 8/29 95/1966 92/2012 FRI 8/30 97/2012 96/1941 SAT 8/31 95/1953 93/1960 SUN 9/1 98/1913 94/1937 MON 9/2 98/1937 94/1929 NORMAL HIGH TEMPERATURES THROUGH THIS PERIOD ARE 78-80 AT LA CROSSE AND 76-78 AT ROCHESTER. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...DAS LONG TERM....DAS AVIATION.....RIECK CLIMATE......DAS/AJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1220 PM CDT FRI AUG 23 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 258 AM CDT FRI AUG 23 2013 MAIN FORECAST CONCERN IN THE SHORT TERM IS ON PRECIPITATION CHANCES TONIGHT. CURRENTLY AS OF 07Z... WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED TROUGHING JUST OFF THE WEST COAST OF THE U.S....RIDGING COVERING MUCH OF THE PLAINS...AND TROUGHING IN SOUTHEAST CANADA. VARIOUS MONSOONAL RELATED SHORTWAVES WERE ROTATING AROUND THE UPPER RIDGE ACROSS THE U.S. ROCKIES...WITH THE MAIN SYNOPTIC SHORTWAVE OF NOTE OVER OREGON. THE FORECAST AREA LIES IN THE INFLECTION OF THE RIDGE AND TROUGH...RESULTING IN SUBSIDENCE AND DRYING. THIS IS REFLECTED WELL BY HIGH PRESSURE THAT IS CENTERED OVER UPPER MICHIGAN...ALONG WITH 00Z RAOBS FROM MPX AND GRB WHICH HAD PRECIPITABLE WATER VALUES OF 0.94 AND 0.81 RESPECTIVELY. THESE VALUES ARE MUCH LOWER THAN THE 1.8-2 INCH VALUES THAT WERE PRESENT ALONG/SOUTH OF I-90 AT 12Z YESTERDAY WITH THE MCS THAT ROLLED THROUGH. LIGHT WINDS ASSOCIATED WITH THE HIGH...GOOD RADIATIONAL COOLING CONDITIONS...RECENT RAIN AND SURFACE DEWPOINTS WHICH CLIMBED FROM EVENING EVAPOTRANSPORATION HAS LED TO SOME FOG. THE THICKEST FOG IS OVER NORTHEAST IA AND FAR SOUTHWEST WI WHERE A DENSE FOG ADVISORY WAS JUST ISSUED. AIRMASS OVER THE FORECAST AREA REMAINS RELATIVELY WARM WITH 850MB READINGS OF 14-16C...WHICH ARE NORMAL. HOWEVER...TO THE WEST...MUCH WARMER 850MB TEMPS OF 20-25C HAVE SPREAD NORTH FROM THE CENTRAL PLAINS INTO MONTANA. SYNOPTIC OVERVIEW... MODELS ARE IN GOOD AGREEMENT PUSHING THE UPPER RIDGE GRADUALLY EASTWARD DURING THE NEXT 24 HOURS...SUCH THAT AT 12Z SATURDAY THE RIDGE AXIS EXTENDS INTO MINNESOTA WITH THE SUBTROPICAL HIGH CENTERED OVER KANSAS AND MISSOURI. THE BIGGEST CONCERN IS ON THE MONSOONAL SHORTWAVES ROTATING AROUND THE RIDGE. ONE SUCH SHORTWAVE MODELS SUGGEST COMING ACROSS THE DAKOTAS INTO WESTERN MINNESOTA TONIGHT...WHICH COULD TRY TO SPREAD SOME PRECIP EAST TOWARDS THE FORECAST AREA. DETAILS... QUIET CONDITIONS TODAY WITH THE FORECAST AREA UNDER THE INFLUENCE OF THE HIGH PRESSURE AREA OVER UPPER MICHIGAN. NOTE THAT THE HIGH DOES START DRIFTING OFF TO THE EAST...WHICH IN TURN DEVELOPS A RETURN SOUTHERLY FLOW OVER THE FORECAST AREA. THIS RETURN FLOW HELPS TO DEFLECT THE BRIEF COOLING THE HIGH BRINGS IN THIS MORNING...CAUSING HIGH TEMPERATURES TODAY TO END UP SIMILAR TO YESTERDAY. NOTE ANY FOG SHOULD MIX OUT QUICKLY BETWEEN 9-10 AM. HEADING INTO TONIGHT...AS THE SHORTWAVE COMES INTO THE DAKOTAS... DPVA ASSOCIATED WITH IT LOOKS TO INTERACT WITH THE NOCTURNAL INCREASE OF THE LOW LEVEL JET. 850MB MOISTURE TRANSPORT PROGS FROM THE 23.00Z NAM/GFS/REGIONAL CANADIAN AND ECMWF ALL POINT TO CONVECTION BREAKING OUT ACROSS EASTERN SOUTH DAKOTA THIS EVENING... ON THE NOSE OF ENHANCED MOISTURE TRANSPORT WITHIN THE LOW LEVEL JET. THIS CONVECTION THEN TRANSLATES EAST. MODEL CONSENSUS WOULD SUGGEST THE BULK OF THE CONVECTION STAYS WEST OF THE AREA PRIOR TO 12Z SATURDAY...BUT DID INCLUDE A 20-30 PERCENT CHANCE OVER WESTERN PORTIONS OF THE FORECAST AREA IN THE EVENT SOME STORMS FORM ON THE EASTERN EDGE OF THE MOISTURE TRANSPORT AS INDICATED BY THE 23.00Z NAM. COMBINATION OF INCREASING MID CLOUDS WITH THE MOISTURE TRANSPORT...AS WELL AS SURFACE WINDS...WILL RESULT IN A WARMER NIGHT. A BLEND OF MODEL GUIDANCE LOOKS REASONABLE FOR LOWS. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 258 AM CDT FRI AUG 23 2013 HAZARDS... THE BIG ONE HERE IS HEAT. A LONG DURATION HEAT EVENT APPEARS LIKELY...BEGINNING ON SUNDAY AND MOSTLY LASTING THROUGH THE REST OF THE LONG TERM PERIOD AND BEYOND. HOWEVER...WEDNESDAY AND THURSDAY ARE MOST PROBLEMATIC AND HAVE PRECLUDED ISSUING ANY HEAT HAZARDS AT THIS TIME. SOME HEAT HAZARDS WILL BE NEEDED EVENTUALLY... ESPECIALLY FOR MONDAY AND TUESDAY. SYNOPTIC OVERVIEW... 23.00Z ECMWF/GFS/CANADIAN AND THE PORTION OF THE NAM THROUGH 84 HOURS ARE ALL IN GOOD AGREEMENT THAT THE UPPER PATTERN CHANGES VERY LITTLE FROM WHERE IT ENDS UP AT 12Z SATURDAY THROUGH THE ENTIRE LONG TERM PERIOD. THE UPPER RIDGE AXIS APPEARS TO STAY CENTERED OVER MINNESOTA WHILE THE SUBTROPICAL HIGH CENTER STRENGTHENS OVER KANSAS AND MISSOURI DURING THE WEEKEND. VARIOUS SHORTWAVES OF MONSOONAL ORIGIN AND ENHANCED BY CONVECTION WILL ROTATE AROUND THE RIDGE... MOST OF WHICH APPEAR TO TAKE A TRACK THROUGH THE DAKOTAS...NORTHERN MINNESOTA AND THROUGH MICHIGAN AND NORTHERN WISCONSIN. THIS IS A PATTERN MORE TYPICAL OF JULY OR EARLY AUGUST VERSUS LATE AUGUST. THE BIG FORECAST QUESTION FROM THE PRECIPITATION SIDE OF THINGS WILL BE DOES ANY CONVECTION ASSOCIATED WITH THE SHORTWAVES DROP SOUTH INTO THE FORECAST AREA. OTHERWISE...ITS ALL ABOUT HOW HOT IT WILL BE. PRECIPITATION DETAILS... FOR SATURDAY...ALTHOUGH ALL INDICATIONS ARE THAT THE NOSE OF THE 850MB MOISTURE TRANSPORT WILL SHIFT NORTH UP INTO NORTHWEST ONTARIO...THE FORECAST AREA SITS ON THE EASTERN EDGE OF THE MOISTURE TRANSPORT. THE NAM...GFS...ECMWF AND REGIONAL CANADIAN ALL DEVELOP SCATTERED CONVECTION THROUGHOUT THE DAY...DUE TO THE COMBINATION OF THIS MOISTURE TRANSPORT AND ELEVATED INSTABILITY ROOTED AT OR ABOVE 900MB. ADDITIONALLY...WE HAVE THAT SHORTWAVE COMING FROM THE DAKOTAS TO PROVIDE SOME DPVA HELP. THEREFORE... HAVE 20-40 PERCENT CHANCES IN THE FORECAST. 1-6KM SHEAR VALUES OF 20-25 KT SHOULD PRECLUDE ANY ORGANIZED SEVERE THREAT...THOUGH INCREASING PRECIPITABLE WATER VALUES SUGGEST POTENTIAL FOR SOME LOCALLY HEAVY RAIN. PRECIPITATION CHANCES SHOULD BEGIN TO SHIFT NORTH SATURDAY NIGHT WITH THE SHORTWAVE PASSED...THE NOSE OF THE 850MB MOISTURE TRANSPORT CENTERED FROM NORTHWEST ONTARIO INTO UPPER MI AND THE FORECAST AREA BECOMING MORE UNDER THE MOISTURE TRANSPORT STREAM ITSELF. THE 23.00Z GFS IS AN OUTLIER HAVING CONVECTION ALL THE WAY SOUTH TOWARDS DUBUQUE WHEREAS ALL OTHER GUIDANCE SUGGESTS ALONG/NORTH I-94 OR EVEN NORTH OF THE FORECAST AREA. LEANED AWAY FROM THE GFS...WHICH STAYS IN GOOD CONTINUITY WITH THE PREVIOUS FORECAST. HIGH CONFIDENCE THAT CONVECTION WILL STAY WELL OFF TO THE NORTHEAST SUNDAY. ANOTHER MONSOON-RELATED SHORTWAVE IS SUGGESTED BY SOME MODELS TO COME ACROSS NORTHERN PORTIONS OF THE FORECAST AREA SUNDAY NIGHT. THE AIRMASS MAY BE CAPPED OFF EVEN TO ELEVATED CONVECTION...BUT WITH THE 22.12Z ECMWF AND 23.00Z GFS DEPICTING SOME CONVECTION WITH THE SHORTWAVE... FELT A 20-30 PERCENT CHANCE IS NEEDED. 23.00Z ECMWF IS DRY FOR SUNDAY NIGHT...WHICH MAY TURN OUT IN REALITY. FOR MONDAY AND BEYOND...MODELS OCCASIONALLY PRODUCE CONVECTION...PARTICULARLY ALONG AND NORTH AND EAST OF I-94 AS SHORTWAVES ROUND THE RIDGE. FROM A CONSENSUS STANDPOINT...THIS YIELDS 20-30 PERCENT CHANCES NEEDED EACH DAY IN THIS AREA. TEMPERATURE DETAILS... FOR SATURDAY...BETWEEN THE CONVECTION AROUND AS WELL AS INDICATIONS OF PLENTY OF CIRRUS...TEMPERATURES ARE LIKELY NOT TO REACH THEIR MAXIMUM POTENTIAL. 850MB TEMPS CLIMBING TO 16C EAST TO 19C WEST WOULD SUPPORT HIGHS IN THE MID TO PERHAPS UPPER 80S...BUT THE AFOREMENTIONED ISSUES LIKELY TO HOLD HIGH TEMPS 5-10 DEGREES COOLER. TEMPERATURES REALLY BEGIN TO HEAT UP ON SUNDAY. COMBINATION OF 925MB TEMPS CLIMBING TO 26-28C AND A BREEZY SOUTHWEST WIND SHOULD EASILY PROPEL HIGHS INTO THE UPPER 80S TO LOW 90S. THE WINDS ARE ALSO GOING TO ADVECT IN HIGHER DEWPOINTS...LIKELY IN THE UPPER 60S TO LOW 70S. HEAT INDICES AS A RESULT TOP OUT IN THE 95 TO 100 RANGE. MONDAY AND TUESDAY BOTH LOOK HOT AS THE WARM AIR SHIFTS EAST OVER THE FORECAST AREA. 925MB TEMPS RISE FURTHER TO 27-29C...PERHAPS EVEN 30C. WITH PLENTY OF SUN...ESPECIALLY SOUTHWEST OF I-94...HIGHS OF 90-95 SHOULD OCCUR. DEWPOINTS MAY NOT CHANGE MUCH COMPARED TO SUNDAY...CAUSING HEAT INDICES TO LIKELY JUMP TO 100-105. THESE DAYS WILL NEED AT LEAST A HEAT ADVISORY. WEDNESDAY AND THURSDAY BECAME A BIT MORE UNCERTAIN WITH THE 23.00Z ECMWF/UKMET. THEY HAVE A SHORTWAVE TROUGH DIGGING INTO NEW ENGLAND WHICH ALLOWS A BACK DOOR COLD FRONT TO COME THROUGH THE FORECAST AREA. 925MB TEMPS COOL TO 24-26C...WHICH WOULD KEEP HIGHS PERHAPS EVEN BELOW 90. ON THE OTHER HAND...THE 23.00Z GFS DOESNT DROP THE COLD FRONT THROUGH...KEEPING 925MB TEMPS UP BETWEEN 28-32C. FOR NOW FOLLOWED A CONSENSUS...WHICH RESULTS IN THESE DAYS BELOW HEAT ADVISORY CONDITIONS. LOWS WILL STAY QUITE WARM DURING THIS STRETCH...LIKELY IN THE LOW TO MID 70S EVERY NIGHT. GIVEN THE UNCERTAINTY WITH WEDNESDAY AND THURSDAY...AND THE VERY MARGINAL CONDITIONS ON SUNDAY...HAVE NOT ISSUED ANY HEAT HAZARDS AT THIS TIME. NOTE THAT MORE HEAT APPEARS TO BE ON THE WAY FOR LABOR DAY WEEKEND. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 1220 PM CDT FRI AUG 23 2013 RESIDUAL LOWER LEVEL MOISTURE TRAPPED UNDER A SHALLOW INVERSION CONTINUES TO IMPACT THE TAF SITES EARLY THIS AFTERNOON WITH SCT-BKN MVFR CLOUDS/CIGS. DIURNAL WARMING/MIXING IS GRADUALLY RAISING THE CLOUD/CIG HGTS...BUT DISTANCE-SPEED TOOL AND WEAK LOW LEVEL WINDS SHOWS THIS MOISTURE/CLOUDS TO CONTINUE IMPACTING THE TAF SITES INTO MID AFTERNOON. HAVE ADDED SOME SCT-BKN CU/STRATO-CU DECKS TO TAFS THRU 20Z. GOOD VFR THEN EXPECTED LATER THIS AFTERNOON/EVENING AS THESE CLOUDS/MOISTURE MOVE NORTH OF THE TAF SITES. SOME MVFR VSBYS IN HZ/BR EXPECTED LATER TONIGHT...WITH SOUTH TO SOUTHEAST GRADIENT WINDS KEEPING BOUNDARY LAYER STIRRED ENOUGH TO KEEP LATE NIGHT/EARLY MORNING IFR VSBYS IN BR/FG ISOLATED. A WARM FRONT AND INCREASING MOISTURE/LIFT IN THE 850-700MB LAYER SPREADS NORTHEAST ACROSS THE AREA LATER TONIGHT/SAT. WIDELY SCT TO SCT SHRA AND A FEW TSRA EXPECTED AS THIS FRONT/FORCING MOVE ACROSS THE TAF SITES. LEFT THIS VCSH AT BOTH KRST/KLSE WITH BKN CIGS IN THE 4K-5K FT RANGE AS THE FRONT PASSES. ANY CLOUDS/CIGS BEHIND THE WARM FRONT ON SAT SHOULD REMAIN ABOVE THE 4K-5K FT LEVEL. && .CLIMATE... ISSUED AT 343 AM CDT FRI AUG 23 2013 GIVEN THE UPCOMING STRETCH OF HEAT...HERE ARE SOME RECORD HIGHS FOR LA CROSSE AND ROCHESTER THROUGH LABOR DAY WEEKEND. MORE CLIMATE INFORMATION CAN BE FOUND ON OUR WEBSITE IN THE TOP NEWS STORY ON THE HEAT. LA CROSSE ROCHESTER --------- --------- SUN 8/25 97/1948 97/1948 MON 8/26 96/1991 95/1955 TUE 8/27 95/1973 93/1984 WED 8/28 97/1955 96/1955 THU 8/29 95/1966 92/2012 FRI 8/30 97/2012 96/1941 SAT 8/31 95/1953 93/1960 SUN 9/1 98/1913 94/1937 MON 9/2 98/1937 94/1929 NORMAL HIGHS ARE 78-80 AT LA CROSSE AND 76-78 AT ROCHESTER. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...AJ LONG TERM....AJ AVIATION.....RRS CLIMATE......AJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
657 AM CDT FRI AUG 23 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 258 AM CDT FRI AUG 23 2013 MAIN FORECAST CONCERN IN THE SHORT TERM IS ON PRECIPITATION CHANCES TONIGHT. CURRENTLY AS OF 07Z... WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED TROUGHING JUST OFF THE WEST COAST OF THE U.S....RIDGING COVERING MUCH OF THE PLAINS...AND TROUGHING IN SOUTHEAST CANADA. VARIOUS MONSOONAL RELATED SHORTWAVES WERE ROTATING AROUND THE UPPER RIDGE ACROSS THE U.S. ROCKIES...WITH THE MAIN SYNOPTIC SHORTWAVE OF NOTE OVER OREGON. THE FORECAST AREA LIES IN THE INFLECTION OF THE RIDGE AND TROUGH...RESULTING IN SUBSIDENCE AND DRYING. THIS IS REFLECTED WELL BY HIGH PRESSURE THAT IS CENTERED OVER UPPER MICHIGAN...ALONG WITH 00Z RAOBS FROM MPX AND GRB WHICH HAD PRECIPITABLE WATER VALUES OF 0.94 AND 0.81 RESPECTIVELY. THESE VALUES ARE MUCH LOWER THAN THE 1.8-2 INCH VALUES THAT WERE PRESENT ALONG/SOUTH OF I-90 AT 12Z YESTERDAY WITH THE MCS THAT ROLLED THROUGH. LIGHT WINDS ASSOCIATED WITH THE HIGH...GOOD RADIATIONAL COOLING CONDITIONS...RECENT RAIN AND SURFACE DEWPOINTS WHICH CLIMBED FROM EVENING EVAPOTRANSPORATION HAS LED TO SOME FOG. THE THICKEST FOG IS OVER NORTHEAST IA AND FAR SOUTHWEST WI WHERE A DENSE FOG ADVISORY WAS JUST ISSUED. AIRMASS OVER THE FORECAST AREA REMAINS RELATIVELY WARM WITH 850MB READINGS OF 14-16C...WHICH ARE NORMAL. HOWEVER...TO THE WEST...MUCH WARMER 850MB TEMPS OF 20-25C HAVE SPREAD NORTH FROM THE CENTRAL PLAINS INTO MONTANA. SYNOPTIC OVERVIEW... MODELS ARE IN GOOD AGREEMENT PUSHING THE UPPER RIDGE GRADUALLY EASTWARD DURING THE NEXT 24 HOURS...SUCH THAT AT 12Z SATURDAY THE RIDGE AXIS EXTENDS INTO MINNESOTA WITH THE SUBTROPICAL HIGH CENTERED OVER KANSAS AND MISSOURI. THE BIGGEST CONCERN IS ON THE MONSOONAL SHORTWAVES ROTATING AROUND THE RIDGE. ONE SUCH SHORTWAVE MODELS SUGGEST COMING ACROSS THE DAKOTAS INTO WESTERN MINNESOTA TONIGHT...WHICH COULD TRY TO SPREAD SOME PRECIP EAST TOWARDS THE FORECAST AREA. DETAILS... QUIET CONDITIONS TODAY WITH THE FORECAST AREA UNDER THE INFLUENCE OF THE HIGH PRESSURE AREA OVER UPPER MICHIGAN. NOTE THAT THE HIGH DOES START DRIFTING OFF TO THE EAST...WHICH IN TURN DEVELOPS A RETURN SOUTHERLY FLOW OVER THE FORECAST AREA. THIS RETURN FLOW HELPS TO DEFLECT THE BRIEF COOLING THE HIGH BRINGS IN THIS MORNING...CAUSING HIGH TEMPERATURES TODAY TO END UP SIMILAR TO YESTERDAY. NOTE ANY FOG SHOULD MIX OUT QUICKLY BETWEEN 9-10 AM. HEADING INTO TONIGHT...AS THE SHORTWAVE COMES INTO THE DAKOTAS... DPVA ASSOCIATED WITH IT LOOKS TO INTERACT WITH THE NOCTURNAL INCREASE OF THE LOW LEVEL JET. 850MB MOISTURE TRANSPORT PROGS FROM THE 23.00Z NAM/GFS/REGIONAL CANADIAN AND ECMWF ALL POINT TO CONVECTION BREAKING OUT ACROSS EASTERN SOUTH DAKOTA THIS EVENING... ON THE NOSE OF ENHANCED MOISTURE TRANSPORT WITHIN THE LOW LEVEL JET. THIS CONVECTION THEN TRANSLATES EAST. MODEL CONSENSUS WOULD SUGGEST THE BULK OF THE CONVECTION STAYS WEST OF THE AREA PRIOR TO 12Z SATURDAY...BUT DID INCLUDE A 20-30 PERCENT CHANCE OVER WESTERN PORTIONS OF THE FORECAST AREA IN THE EVENT SOME STORMS FORM ON THE EASTERN EDGE OF THE MOISTURE TRANSPORT AS INDICATED BY THE 23.00Z NAM. COMBINATION OF INCREASING MID CLOUDS WITH THE MOISTURE TRANSPORT...AS WELL AS SURFACE WINDS...WILL RESULT IN A WARMER NIGHT. A BLEND OF MODEL GUIDANCE LOOKS REASONABLE FOR LOWS. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 258 AM CDT FRI AUG 23 2013 HAZARDS... THE BIG ONE HERE IS HEAT. A LONG DURATION HEAT EVENT APPEARS LIKELY...BEGINNING ON SUNDAY AND MOSTLY LASTING THROUGH THE REST OF THE LONG TERM PERIOD AND BEYOND. HOWEVER...WEDNESDAY AND THURSDAY ARE MOST PROBLEMATIC AND HAVE PRECLUDED ISSUING ANY HEAT HAZARDS AT THIS TIME. SOME HEAT HAZARDS WILL BE NEEDED EVENTUALLY... ESPECIALLY FOR MONDAY AND TUESDAY. SYNOPTIC OVERVIEW... 23.00Z ECMWF/GFS/CANADIAN AND THE PORTION OF THE NAM THROUGH 84 HOURS ARE ALL IN GOOD AGREEMENT THAT THE UPPER PATTERN CHANGES VERY LITTLE FROM WHERE IT ENDS UP AT 12Z SATURDAY THROUGH THE ENTIRE LONG TERM PERIOD. THE UPPER RIDGE AXIS APPEARS TO STAY CENTERED OVER MINNESOTA WHILE THE SUBTROPICAL HIGH CENTER STRENGTHENS OVER KANSAS AND MISSOURI DURING THE WEEKEND. VARIOUS SHORTWAVES OF MONSOONAL ORIGIN AND ENHANCED BY CONVECTION WILL ROTATE AROUND THE RIDGE... MOST OF WHICH APPEAR TO TAKE A TRACK THROUGH THE DAKOTAS...NORTHERN MINNESOTA AND THROUGH MICHIGAN AND NORTHERN WISCONSIN. THIS IS A PATTERN MORE TYPICAL OF JULY OR EARLY AUGUST VERSUS LATE AUGUST. THE BIG FORECAST QUESTION FROM THE PRECIPITATION SIDE OF THINGS WILL BE DOES ANY CONVECTION ASSOCIATED WITH THE SHORTWAVES DROP SOUTH INTO THE FORECAST AREA. OTHERWISE...ITS ALL ABOUT HOW HOT IT WILL BE. PRECIPITATION DETAILS... FOR SATURDAY...ALTHOUGH ALL INDICATIONS ARE THAT THE NOSE OF THE 850MB MOISTURE TRANSPORT WILL SHIFT NORTH UP INTO NORTHWEST ONTARIO...THE FORECAST AREA SITS ON THE EASTERN EDGE OF THE MOISTURE TRANSPORT. THE NAM...GFS...ECMWF AND REGIONAL CANADIAN ALL DEVELOP SCATTERED CONVECTION THROUGHOUT THE DAY...DUE TO THE COMBINATION OF THIS MOISTURE TRANSPORT AND ELEVATED INSTABILITY ROOTED AT OR ABOVE 900MB. ADDITIONALLY...WE HAVE THAT SHORTWAVE COMING FROM THE DAKOTAS TO PROVIDE SOME DPVA HELP. THEREFORE... HAVE 20-40 PERCENT CHANCES IN THE FORECAST. 1-6KM SHEAR VALUES OF 20-25 KT SHOULD PRECLUDE ANY ORGANIZED SEVERE THREAT...THOUGH INCREASING PRECIPITABLE WATER VALUES SUGGEST POTENTIAL FOR SOME LOCALLY HEAVY RAIN. PRECIPITATION CHANCES SHOULD BEGIN TO SHIFT NORTH SATURDAY NIGHT WITH THE SHORTWAVE PASSED...THE NOSE OF THE 850MB MOISTURE TRANSPORT CENTERED FROM NORTHWEST ONTARIO INTO UPPER MI AND THE FORECAST AREA BECOMING MORE UNDER THE MOISTURE TRANSPORT STREAM ITSELF. THE 23.00Z GFS IS AN OUTLIER HAVING CONVECTION ALL THE WAY SOUTH TOWARDS DUBUQUE WHEREAS ALL OTHER GUIDANCE SUGGESTS ALONG/NORTH I-94 OR EVEN NORTH OF THE FORECAST AREA. LEANED AWAY FROM THE GFS...WHICH STAYS IN GOOD CONTINUITY WITH THE PREVIOUS FORECAST. HIGH CONFIDENCE THAT CONVECTION WILL STAY WELL OFF TO THE NORTHEAST SUNDAY. ANOTHER MONSOON-RELATED SHORTWAVE IS SUGGESTED BY SOME MODELS TO COME ACROSS NORTHERN PORTIONS OF THE FORECAST AREA SUNDAY NIGHT. THE AIRMASS MAY BE CAPPED OFF EVEN TO ELEVATED CONVECTION...BUT WITH THE 22.12Z ECMWF AND 23.00Z GFS DEPICTING SOME CONVECTION WITH THE SHORTWAVE... FELT A 20-30 PERCENT CHANCE IS NEEDED. 23.00Z ECMWF IS DRY FOR SUNDAY NIGHT...WHICH MAY TURN OUT IN REALITY. FOR MONDAY AND BEYOND...MODELS OCCASIONALLY PRODUCE CONVECTION...PARTICULARLY ALONG AND NORTH AND EAST OF I-94 AS SHORTWAVES ROUND THE RIDGE. FROM A CONSENSUS STANDPOINT...THIS YIELDS 20-30 PERCENT CHANCES NEEDED EACH DAY IN THIS AREA. TEMPERATURE DETAILS... FOR SATURDAY...BETWEEN THE CONVECTION AROUND AS WELL AS INDICATIONS OF PLENTY OF CIRRUS...TEMPERATURES ARE LIKELY NOT TO REACH THEIR MAXIMUM POTENTIAL. 850MB TEMPS CLIMBING TO 16C EAST TO 19C WEST WOULD SUPPORT HIGHS IN THE MID TO PERHAPS UPPER 80S...BUT THE AFOREMENTIONED ISSUES LIKELY TO HOLD HIGH TEMPS 5-10 DEGREES COOLER. TEMPERATURES REALLY BEGIN TO HEAT UP ON SUNDAY. COMBINATION OF 925MB TEMPS CLIMBING TO 26-28C AND A BREEZY SOUTHWEST WIND SHOULD EASILY PROPEL HIGHS INTO THE UPPER 80S TO LOW 90S. THE WINDS ARE ALSO GOING TO ADVECT IN HIGHER DEWPOINTS...LIKELY IN THE UPPER 60S TO LOW 70S. HEAT INDICES AS A RESULT TOP OUT IN THE 95 TO 100 RANGE. MONDAY AND TUESDAY BOTH LOOK HOT AS THE WARM AIR SHIFTS EAST OVER THE FORECAST AREA. 925MB TEMPS RISE FURTHER TO 27-29C...PERHAPS EVEN 30C. WITH PLENTY OF SUN...ESPECIALLY SOUTHWEST OF I-94...HIGHS OF 90-95 SHOULD OCCUR. DEWPOINTS MAY NOT CHANGE MUCH COMPARED TO SUNDAY...CAUSING HEAT INDICES TO LIKELY JUMP TO 100-105. THESE DAYS WILL NEED AT LEAST A HEAT ADVISORY. WEDNESDAY AND THURSDAY BECAME A BIT MORE UNCERTAIN WITH THE 23.00Z ECMWF/UKMET. THEY HAVE A SHORTWAVE TROUGH DIGGING INTO NEW ENGLAND WHICH ALLOWS A BACK DOOR COLD FRONT TO COME THROUGH THE FORECAST AREA. 925MB TEMPS COOL TO 24-26C...WHICH WOULD KEEP HIGHS PERHAPS EVEN BELOW 90. ON THE OTHER HAND...THE 23.00Z GFS DOESNT DROP THE COLD FRONT THROUGH...KEEPING 925MB TEMPS UP BETWEEN 28-32C. FOR NOW FOLLOWED A CONSENSUS...WHICH RESULTS IN THESE DAYS BELOW HEAT ADVISORY CONDITIONS. LOWS WILL STAY QUITE WARM DURING THIS STRETCH...LIKELY IN THE LOW TO MID 70S EVERY NIGHT. GIVEN THE UNCERTAINTY WITH WEDNESDAY AND THURSDAY...AND THE VERY MARGINAL CONDITIONS ON SUNDAY...HAVE NOT ISSUED ANY HEAT HAZARDS AT THIS TIME. NOTE THAT MORE HEAT APPEARS TO BE ON THE WAY FOR LABOR DAY WEEKEND. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 654 AM CDT FRI AUG 23 2013 THE COMBINATION OF LIGHT WINDS AND CLEAR SKIES RESULTED IN THE DEVELOPMENT OF VALLEY FOG OVERNIGHT. AS HAS BEEN THE CASE DURING THE PAST WEEK...THE RECENT DRYNESS HAS BEEN CAUSING WIDE RANGING VISIBILITIES IN VALLEY AS IT MEANDERS THROUGH RIVER CHANNLE. KLSE HAS RANGED FROM LITTLE AS A HALF MILE TO NOW 8 MILES...SO CONFIDENCE IS ABOUT 60 PERCENT THAT A QUARTER MILE OR LESS WILL MAKE IT BACK OVER THE AIR FIELD. BASED ON THE TIME OF YEAR...EXPECT THAT THIS FOG WILL DISSIPATE RAPIDLY BETWEEN 23.14Z AND 23.15Z. FOR LATE TONIGHT...EXPECT A 4-5K DECK OF CLOUDS TO MOVE INTO THE AREA AFTER 24.06Z AS A WARM FRONT APPROACHES THE AREA FROM WESTERN MINNESOTA AND WESTERN IOWA. A FEW SHOWERS AND THUNDERSTORMS MAY AFFECT KRST AFTER 24.10Z. HOWEVER CONFIDENCE WAS TOO LOW TO INCLUDE IN THE TAF AT THIS TIME. && .CLIMATE... ISSUED AT 343 AM CDT FRI AUG 23 2013 GIVEN THE UPCOMING STRETCH OF HEAT...HERE ARE SOME RECORD HIGHS FOR LA CROSSE AND ROCHESTER THROUGH LABOR DAY WEEKEND. MORE CLIMATE INFORMATION CAN BE FOUND ON OUR WEBSITE IN THE TOP NEWS STORY ON THE HEAT. LA CROSSE ROCHESTER --------- --------- SUN 8/25 97/1948 97/1948 MON 8/26 96/1991 95/1955 TUE 8/27 95/1973 93/1984 WED 8/28 97/1955 96/1955 THU 8/29 95/1966 92/2012 FRI 8/30 97/2012 96/1941 SAT 8/31 95/1953 93/1960 SUN 9/1 98/1913 94/1937 MON 9/2 98/1937 94/1929 NORMAL HIGHS ARE 78-80 AT LA CROSSE AND 76-78 AT ROCHESTER. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR WIZ054-055- 061. MN...NONE. IA...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR IAZ008>011- 018-019-029-030. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION...BOYNE CLIMATE...AJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
343 AM CDT FRI AUG 23 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 258 AM CDT FRI AUG 23 2013 MAIN FORECAST CONCERN IN THE SHORT TERM IS ON PRECIPITATION CHANCES TONIGHT. CURRENTLY AS OF 07Z... WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED TROUGHING JUST OFF THE WEST COAST OF THE U.S....RIDGING COVERING MUCH OF THE PLAINS...AND TROUGHING IN SOUTHEAST CANADA. VARIOUS MONSOONAL RELATED SHORTWAVES WERE ROTATING AROUND THE UPPER RIDGE ACROSS THE U.S. ROCKIES...WITH THE MAIN SYNOPTIC SHORTWAVE OF NOTE OVER OREGON. THE FORECAST AREA LIES IN THE INFLECTION OF THE RIDGE AND TROUGH...RESULTING IN SUBSIDENCE AND DRYING. THIS IS REFLECTED WELL BY HIGH PRESSURE THAT IS CENTERED OVER UPPER MICHIGAN...ALONG WITH 00Z RAOBS FROM MPX AND GRB WHICH HAD PRECIPITABLE WATER VALUES OF 0.94 AND 0.81 RESPECTIVELY. THESE VALUES ARE MUCH LOWER THAN THE 1.8-2 INCH VALUES THAT WERE PRESENT ALONG/SOUTH OF I-90 AT 12Z YESTERDAY WITH THE MCS THAT ROLLED THROUGH. LIGHT WINDS ASSOCIATED WITH THE HIGH...GOOD RADIATIONAL COOLING CONDITIONS...RECENT RAIN AND SURFACE DEWPOINTS WHICH CLIMBED FROM EVENING EVAPOTRANSPORATION HAS LED TO SOME FOG. THE THICKEST FOG IS OVER NORTHEAST IA AND FAR SOUTHWEST WI WHERE A DENSE FOG ADVISORY WAS JUST ISSUED. AIRMASS OVER THE FORECAST AREA REMAINS RELATIVELY WARM WITH 850MB READINGS OF 14-16C...WHICH ARE NORMAL. HOWEVER...TO THE WEST...MUCH WARMER 850MB TEMPS OF 20-25C HAVE SPREAD NORTH FROM THE CENTRAL PLAINS INTO MONTANA. SYNOPTIC OVERVIEW... MODELS ARE IN GOOD AGREEMENT PUSHING THE UPPER RIDGE GRADUALLY EASTWARD DURING THE NEXT 24 HOURS...SUCH THAT AT 12Z SATURDAY THE RIDGE AXIS EXTENDS INTO MINNESOTA WITH THE SUBTROPICAL HIGH CENTERED OVER KANSAS AND MISSOURI. THE BIGGEST CONCERN IS ON THE MONSOONAL SHORTWAVES ROTATING AROUND THE RIDGE. ONE SUCH SHORTWAVE MODELS SUGGEST COMING ACROSS THE DAKOTAS INTO WESTERN MINNESOTA TONIGHT...WHICH COULD TRY TO SPREAD SOME PRECIP EAST TOWARDS THE FORECAST AREA. DETAILS... QUIET CONDITIONS TODAY WITH THE FORECAST AREA UNDER THE INFLUENCE OF THE HIGH PRESSURE AREA OVER UPPER MICHIGAN. NOTE THAT THE HIGH DOES START DRIFTING OFF TO THE EAST...WHICH IN TURN DEVELOPS A RETURN SOUTHERLY FLOW OVER THE FORECAST AREA. THIS RETURN FLOW HELPS TO DEFLECT THE BRIEF COOLING THE HIGH BRINGS IN THIS MORNING...CAUSING HIGH TEMPERATURES TODAY TO END UP SIMILAR TO YESTERDAY. NOTE ANY FOG SHOULD MIX OUT QUICKLY BETWEEN 9-10 AM. HEADING INTO TONIGHT...AS THE SHORTWAVE COMES INTO THE DAKOTAS... DPVA ASSOCIATED WITH IT LOOKS TO INTERACT WITH THE NOCTURNAL INCREASE OF THE LOW LEVEL JET. 850MB MOISTURE TRANSPORT PROGS FROM THE 23.00Z NAM/GFS/REGIONAL CANADIAN AND ECMWF ALL POINT TO CONVECTION BREAKING OUT ACROSS EASTERN SOUTH DAKOTA THIS EVENING... ON THE NOSE OF ENHANCED MOISTURE TRANSPORT WITHIN THE LOW LEVEL JET. THIS CONVECTION THEN TRANSLATES EAST. MODEL CONSENSUS WOULD SUGGEST THE BULK OF THE CONVECTION STAYS WEST OF THE AREA PRIOR TO 12Z SATURDAY...BUT DID INCLUDE A 20-30 PERCENT CHANCE OVER WESTERN PORTIONS OF THE FORECAST AREA IN THE EVENT SOME STORMS FORM ON THE EASTERN EDGE OF THE MOISTURE TRANSPORT AS INDICATED BY THE 23.00Z NAM. COMBINATION OF INCREASING MID CLOUDS WITH THE MOISTURE TRANSPORT...AS WELL AS SURFACE WINDS...WILL RESULT IN A WARMER NIGHT. A BLEND OF MODEL GUIDANCE LOOKS REASONABLE FOR LOWS. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 258 AM CDT FRI AUG 23 2013 HAZARDS... THE BIG ONE HERE IS HEAT. A LONG DURATION HEAT EVENT APPEARS LIKELY...BEGINNING ON SUNDAY AND MOSTLY LASTING THROUGH THE REST OF THE LONG TERM PERIOD AND BEYOND. HOWEVER...WEDNESDAY AND THURSDAY ARE MOST PROBLEMATIC AND HAVE PRECLUDED ISSUING ANY HEAT HAZARDS AT THIS TIME. SOME HEAT HAZARDS WILL BE NEEDED EVENTUALLY... ESPECIALLY FOR MONDAY AND TUESDAY. SYNOPTIC OVERVIEW... 23.00Z ECMWF/GFS/CANADIAN AND THE PORTION OF THE NAM THROUGH 84 HOURS ARE ALL IN GOOD AGREEMENT THAT THE UPPER PATTERN CHANGES VERY LITTLE FROM WHERE IT ENDS UP AT 12Z SATURDAY THROUGH THE ENTIRE LONG TERM PERIOD. THE UPPER RIDGE AXIS APPEARS TO STAY CENTERED OVER MINNESOTA WHILE THE SUBTROPICAL HIGH CENTER STRENGTHENS OVER KANSAS AND MISSOURI DURING THE WEEKEND. VARIOUS SHORTWAVES OF MONSOONAL ORIGIN AND ENHANCED BY CONVECTION WILL ROTATE AROUND THE RIDGE... MOST OF WHICH APPEAR TO TAKE A TRACK THROUGH THE DAKOTAS...NORTHERN MINNESOTA AND THROUGH MICHIGAN AND NORTHERN WISCONSIN. THIS IS A PATTERN MORE TYPICAL OF JULY OR EARLY AUGUST VERSUS LATE AUGUST. THE BIG FORECAST QUESTION FROM THE PRECIPITATION SIDE OF THINGS WILL BE DOES ANY CONVECTION ASSOCIATED WITH THE SHORTWAVES DROP SOUTH INTO THE FORECAST AREA. OTHERWISE...ITS ALL ABOUT HOW HOT IT WILL BE. PRECIPITATION DETAILS... FOR SATURDAY...ALTHOUGH ALL INDICATIONS ARE THAT THE NOSE OF THE 850MB MOISTURE TRANSPORT WILL SHIFT NORTH UP INTO NORTHWEST ONTARIO...THE FORECAST AREA SITS ON THE EASTERN EDGE OF THE MOISTURE TRANSPORT. THE NAM...GFS...ECMWF AND REGIONAL CANADIAN ALL DEVELOP SCATTERED CONVECTION THROUGHOUT THE DAY...DUE TO THE COMBINATION OF THIS MOISTURE TRANSPORT AND ELEVATED INSTABILITY ROOTED AT OR ABOVE 900MB. ADDITIONALLY...WE HAVE THAT SHORTWAVE COMING FROM THE DAKOTAS TO PROVIDE SOME DPVA HELP. THEREFORE... HAVE 20-40 PERCENT CHANCES IN THE FORECAST. 1-6KM SHEAR VALUES OF 20-25 KT SHOULD PRECLUDE ANY ORGANIZED SEVERE THREAT...THOUGH INCREASING PRECIPITABLE WATER VALUES SUGGEST POTENTIAL FOR SOME LOCALLY HEAVY RAIN. PRECIPITATION CHANCES SHOULD BEGIN TO SHIFT NORTH SATURDAY NIGHT WITH THE SHORTWAVE PASSED...THE NOSE OF THE 850MB MOISTURE TRANSPORT CENTERED FROM NORTHWEST ONTARIO INTO UPPER MI AND THE FORECAST AREA BECOMING MORE UNDER THE MOISTURE TRANSPORT STREAM ITSELF. THE 23.00Z GFS IS AN OUTLIER HAVING CONVECTION ALL THE WAY SOUTH TOWARDS DUBUQUE WHEREAS ALL OTHER GUIDANCE SUGGESTS ALONG/NORTH I-94 OR EVEN NORTH OF THE FORECAST AREA. LEANED AWAY FROM THE GFS...WHICH STAYS IN GOOD CONTINUITY WITH THE PREVIOUS FORECAST. HIGH CONFIDENCE THAT CONVECTION WILL STAY WELL OFF TO THE NORTHEAST SUNDAY. ANOTHER MONSOON-RELATED SHORTWAVE IS SUGGESTED BY SOME MODELS TO COME ACROSS NORTHERN PORTIONS OF THE FORECAST AREA SUNDAY NIGHT. THE AIRMASS MAY BE CAPPED OFF EVEN TO ELEVATED CONVECTION...BUT WITH THE 22.12Z ECMWF AND 23.00Z GFS DEPICTING SOME CONVECTION WITH THE SHORTWAVE... FELT A 20-30 PERCENT CHANCE IS NEEDED. 23.00Z ECMWF IS DRY FOR SUNDAY NIGHT...WHICH MAY TURN OUT IN REALITY. FOR MONDAY AND BEYOND...MODELS OCCASIONALLY PRODUCE CONVECTION...PARTICULARLY ALONG AND NORTH AND EAST OF I-94 AS SHORTWAVES ROUND THE RIDGE. FROM A CONSENSUS STANDPOINT...THIS YIELDS 20-30 PERCENT CHANCES NEEDED EACH DAY IN THIS AREA. TEMPERATURE DETAILS... FOR SATURDAY...BETWEEN THE CONVECTION AROUND AS WELL AS INDICATIONS OF PLENTY OF CIRRUS...TEMPERATURES ARE LIKELY NOT TO REACH THEIR MAXIMUM POTENTIAL. 850MB TEMPS CLIMBING TO 16C EAST TO 19C WEST WOULD SUPPORT HIGHS IN THE MID TO PERHAPS UPPER 80S...BUT THE AFOREMENTIONED ISSUES LIKELY TO HOLD HIGH TEMPS 5-10 DEGREES COOLER. TEMPERATURES REALLY BEGIN TO HEAT UP ON SUNDAY. COMBINATION OF 925MB TEMPS CLIMBING TO 26-28C AND A BREEZY SOUTHWEST WIND SHOULD EASILY PROPEL HIGHS INTO THE UPPER 80S TO LOW 90S. THE WINDS ARE ALSO GOING TO ADVECT IN HIGHER DEWPOINTS...LIKELY IN THE UPPER 60S TO LOW 70S. HEAT INDICES AS A RESULT TOP OUT IN THE 95 TO 100 RANGE. MONDAY AND TUESDAY BOTH LOOK HOT AS THE WARM AIR SHIFTS EAST OVER THE FORECAST AREA. 925MB TEMPS RISE FURTHER TO 27-29C...PERHAPS EVEN 30C. WITH PLENTY OF SUN...ESPECIALLY SOUTHWEST OF I-94...HIGHS OF 90-95 SHOULD OCCUR. DEWPOINTS MAY NOT CHANGE MUCH COMPARED TO SUNDAY...CAUSING HEAT INDICES TO LIKELY JUMP TO 100-105. THESE DAYS WILL NEED AT LEAST A HEAT ADVISORY. WEDNESDAY AND THURSDAY BECAME A BIT MORE UNCERTAIN WITH THE 23.00Z ECMWF/UKMET. THEY HAVE A SHORTWAVE TROUGH DIGGING INTO NEW ENGLAND WHICH ALLOWS A BACK DOOR COLD FRONT TO COME THROUGH THE FORECAST AREA. 925MB TEMPS COOL TO 24-26C...WHICH WOULD KEEP HIGHS PERHAPS EVEN BELOW 90. ON THE OTHER HAND...THE 23.00Z GFS DOESNT DROP THE COLD FRONT THROUGH...KEEPING 925MB TEMPS UP BETWEEN 28-32C. FOR NOW FOLLOWED A CONSENSUS...WHICH RESULTS IN THESE DAYS BELOW HEAT ADVISORY CONDITIONS. LOWS WILL STAY QUITE WARM DURING THIS STRETCH...LIKELY IN THE LOW TO MID 70S EVERY NIGHT. GIVEN THE UNCERTAINTY WITH WEDNESDAY AND THURSDAY...AND THE VERY MARGINAL CONDITIONS ON SUNDAY...HAVE NOT ISSUED ANY HEAT HAZARDS AT THIS TIME. NOTE THAT MORE HEAT APPEARS TO BE ON THE WAY FOR LABOR DAY WEEKEND. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 1155 PM CDT THU AUG 22 2013 CHALLENGING RIVER VALLEY FOG SETUP FOR KLSE AS A FEW COMPETING FACTORS COULD LEAD TO 1/4SM...OR NOTHING AT ALL. AS HIGH PRESSURE SETTLES TO THE NORTH...SOUTHEASTERLY SURFACE WINDS WILL REMAIN GENERALLY 5 MPH OR LESS. HOWEVER...925 TO 900 MB WINDS ARE EXPECTED TO INCREASE FROM 5 TO 7 MPH THIS EVENING...TO NEARLY 15 TO 20 MPH BY 10Z ACCORDING TO VARIOUS MODEL SOUNDINGS. THIS WIND INCREASE DOES NOT SUPPORT A DENSE FOG EVENT. HOWEVER...THE LATE ARRIVAL OF THIS SPEED MAX COULD ALLOW FOG TO FORM IN THE CHANNEL...THEN TRAP IT BELOW THE INVERSION. ALSO...TRENDS IN THE MODEL SOUNDINGS ARE NOT AS CONSISTENT...AND SOME PREVIOUS RUNS SHOWED A LIGHTER WIND LAYER. ALL IN ALL...WHILE THE WIND ISSUE MAY HURT DENSE FOG CHANCES...NOT SOLD YET THAT IT WILL PRECLUDE DENSE FOG FORMATION. T/TD IS DOWN TO 5 F AS OF 04Z...WITH SFC WINDS REMAINING LIGHT. BOTH FAVORABLE FOR DENSE FOG. KLSE TAF WAS UPDATED BEFORE 03Z TO INCLUDE A PERIOD OF 1/4SM...AND WILL CONTINUE THIS. EXPECT RAPID IMPROVEMENT/CLEARING AROUND 14Z. REST OF THE DAY SHOULD BE VFR...WITH CLOUDS INCREASING OVERNIGHT FRIDAY...AND THE CHANCE FOR SCT SHRA/TS ON SAT. && .CLIMATE... ISSUED AT 343 AM CDT FRI AUG 23 2013 GIVEN THE UPCOMING STRETCH OF HEAT...HERE ARE SOME RECORD HIGHS FOR LA CROSSE AND ROCHESTER THROUGH LABOR DAY WEEKEND. MORE CLIMATE INFORMATION CAN BE FOUND ON OUR WEBSITE IN THE TOP NEWS STORY ON THE HEAT. LA CROSSE ROCHESTER --------- --------- SUN 8/25 97/1948 97/1948 MON 8/26 96/1991 95/1955 TUE 8/27 95/1973 93/1984 WED 8/28 97/1955 96/1955 THU 8/29 95/1966 92/2012 FRI 8/30 97/2012 96/1941 SAT 8/31 95/1953 93/1960 SUN 9/1 98/1913 94/1937 MON 9/2 98/1937 94/1929 NORMAL HIGHS ARE 78-80 AT LA CROSSE AND 76-78 AT ROCHESTER. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR WIZ054-055- 061. MN...NONE. IA...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR IAZ008>011- 018-019-029-030. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION.....ZT/RIECK CLIMATE...AJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
258 AM CDT FRI AUG 23 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 258 AM CDT FRI AUG 23 2013 MAIN FORECAST CONCERN IN THE SHORT TERM IS ON PRECIPITATION CHANCES TONIGHT. CURRENTLY AS OF 07Z... WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED TROUGHING JUST OFF THE WEST COAST OF THE U.S....RIDGING COVERING MUCH OF THE PLAINS...AND TROUGHING IN SOUTHEAST CANADA. VARIOUS MONSOONAL RELATED SHORTWAVES WERE ROTATING AROUND THE UPPER RIDGE ACROSS THE U.S. ROCKIES...WITH THE MAIN SYNOPTIC SHORTWAVE OF NOTE OVER OREGON. THE FORECAST AREA LIES IN THE INFLECTION OF THE RIDGE AND TROUGH...RESULTING IN SUBSIDENCE AND DRYING. THIS IS REFLECTED WELL BY HIGH PRESSURE THAT IS CENTERED OVER UPPER MICHIGAN...ALONG WITH 00Z RAOBS FROM MPX AND GRB WHICH HAD PRECIPITABLE WATER VALUES OF 0.94 AND 0.81 RESPECTIVELY. THESE VALUES ARE MUCH LOWER THAN THE 1.8-2 INCH VALUES THAT WERE PRESENT ALONG/SOUTH OF I-90 AT 12Z YESTERDAY WITH THE MCS THAT ROLLED THROUGH. LIGHT WINDS ASSOCIATED WITH THE HIGH...GOOD RADIATIONAL COOLING CONDITIONS...RECENT RAIN AND SURFACE DEWPOINTS WHICH CLIMBED FROM EVENING EVAPOTRANSPORATION HAS LED TO SOME FOG. THE THICKEST FOG IS OVER NORTHEAST IA AND FAR SOUTHWEST WI WHERE A DENSE FOG ADVISORY WAS JUST ISSUED. AIRMASS OVER THE FORECAST AREA REMAINS RELATIVELY WARM WITH 850MB READINGS OF 14-16C...WHICH ARE NORMAL. HOWEVER...TO THE WEST...MUCH WARMER 850MB TEMPS OF 20-25C HAVE SPREAD NORTH FROM THE CENTRAL PLAINS INTO MONTANA. SYNOPTIC OVERVIEW... MODELS ARE IN GOOD AGREEMENT PUSHING THE UPPER RIDGE GRADUALLY EASTWARD DURING THE NEXT 24 HOURS...SUCH THAT AT 12Z SATURDAY THE RIDGE AXIS EXTENDS INTO MINNESOTA WITH THE SUBTROPICAL HIGH CENTERED OVER KANSAS AND MISSOURI. THE BIGGEST CONCERN IS ON THE MONSOONAL SHORTWAVES ROTATING AROUND THE RIDGE. ONE SUCH SHORTWAVE MODELS SUGGEST COMING ACROSS THE DAKOTAS INTO WESTERN MINNESOTA TONIGHT...WHICH COULD TRY TO SPREAD SOME PRECIP EAST TOWARDS THE FORECAST AREA. DETAILS... QUIET CONDITIONS TODAY WITH THE FORECAST AREA UNDER THE INFLUENCE OF THE HIGH PRESSURE AREA OVER UPPER MICHIGAN. NOTE THAT THE HIGH DOES START DRIFTING OFF TO THE EAST...WHICH IN TURN DEVELOPS A RETURN SOUTHERLY FLOW OVER THE FORECAST AREA. THIS RETURN FLOW HELPS TO DEFLECT THE BRIEF COOLING THE HIGH BRINGS IN THIS MORNING...CAUSING HIGH TEMPERATURES TODAY TO END UP SIMILAR TO YESTERDAY. NOTE ANY FOG SHOULD MIX OUT QUICKLY BETWEEN 9-10 AM. HEADING INTO TONIGHT...AS THE SHORTWAVE COMES INTO THE DAKOTAS... DPVA ASSOCIATED WITH IT LOOKS TO INTERACT WITH THE NOCTURNAL INCREASE OF THE LOW LEVEL JET. 850MB MOISTURE TRANSPORT PROGS FROM THE 23.00Z NAM/GFS/REGIONAL CANADIAN AND ECMWF ALL POINT TO CONVECTION BREAKING OUT ACROSS EASTERN SOUTH DAKOTA THIS EVENING... ON THE NOSE OF ENHANCED MOISTURE TRANSPORT WITHIN THE LOW LEVEL JET. THIS CONVECTION THEN TRANSLATES EAST. MODEL CONSENSUS WOULD SUGGEST THE BULK OF THE CONVECTION STAYS WEST OF THE AREA PRIOR TO 12Z SATURDAY...BUT DID INCLUDE A 20-30 PERCENT CHANCE OVER WESTERN PORTIONS OF THE FORECAST AREA IN THE EVENT SOME STORMS FORM ON THE EASTERN EDGE OF THE MOISTURE TRANSPORT AS INDICATED BY THE 23.00Z NAM. COMBINATION OF INCREASING MID CLOUDS WITH THE MOISTURE TRANSPORT...AS WELL AS SURFACE WINDS...WILL RESULT IN A WARMER NIGHT. A BLEND OF MODEL GUIDANCE LOOKS REASONABLE FOR LOWS. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 258 AM CDT FRI AUG 23 2013 HAZARDS... THE BIG ONE HERE IS HEAT. A LONG DURATION HEAT EVENT APPEARS LIKELY...BEGINNING ON SUNDAY AND MOSTLY LASTING THROUGH THE REST OF THE LONG TERM PERIOD AND BEYOND. HOWEVER...WEDNESDAY AND THURSDAY ARE MOST PROBLEMATIC AND HAVE PRECLUDED ISSUING ANY HEAT HAZARDS AT THIS TIME. SOME HEAT HAZARDS WILL BE NEEDED EVENTUALLY... ESPECIALLY FOR MONDAY AND TUESDAY. SYNOPTIC OVERVIEW... 23.00Z ECMWF/GFS/CANADIAN AND THE PORTION OF THE NAM THROUGH 84 HOURS ARE ALL IN GOOD AGREEMENT THAT THE UPPER PATTERN CHANGES VERY LITTLE FROM WHERE IT ENDS UP AT 12Z SATURDAY THROUGH THE ENTIRE LONG TERM PERIOD. THE UPPER RIDGE AXIS APPEARS TO STAY CENTERED OVER MINNESOTA WHILE THE SUBTROPICAL HIGH CENTER STRENGTHENS OVER KANSAS AND MISSOURI DURING THE WEEKEND. VARIOUS SHORTWAVES OF MONSOONAL ORIGIN AND ENHANCED BY CONVECTION WILL ROTATE AROUND THE RIDGE... MOST OF WHICH APPEAR TO TAKE A TRACK THROUGH THE DAKOTAS...NORTHERN MINNESOTA AND THROUGH MICHIGAN AND NORTHERN WISCONSIN. THIS IS A PATTERN MORE TYPICAL OF JULY OR EARLY AUGUST VERSUS LATE AUGUST. THE BIG FORECAST QUESTION FROM THE PRECIPITATION SIDE OF THINGS WILL BE DOES ANY CONVECTION ASSOCIATED WITH THE SHORTWAVES DROP SOUTH INTO THE FORECAST AREA. OTHERWISE...ITS ALL ABOUT HOW HOT IT WILL BE. PRECIPITATION DETAILS... FOR SATURDAY...ALTHOUGH ALL INDICATIONS ARE THAT THE NOSE OF THE 850MB MOISTURE TRANSPORT WILL SHIFT NORTH UP INTO NORTHWEST ONTARIO...THE FORECAST AREA SITS ON THE EASTERN EDGE OF THE MOISTURE TRANSPORT. THE NAM...GFS...ECMWF AND REGIONAL CANADIAN ALL DEVELOP SCATTERED CONVECTION THROUGHOUT THE DAY...DUE TO THE COMBINATION OF THIS MOISTURE TRANSPORT AND ELEVATED INSTABILITY ROOTED AT OR ABOVE 900MB. ADDITIONALLY...WE HAVE THAT SHORTWAVE COMING FROM THE DAKOTAS TO PROVIDE SOME DPVA HELP. THEREFORE... HAVE 20-40 PERCENT CHANCES IN THE FORECAST. 1-6KM SHEAR VALUES OF 20-25 KT SHOULD PRECLUDE ANY ORGANIZED SEVERE THREAT...THOUGH INCREASING PRECIPITABLE WATER VALUES SUGGEST POTENTIAL FOR SOME LOCALLY HEAVY RAIN. PRECIPITATION CHANCES SHOULD BEGIN TO SHIFT NORTH SATURDAY NIGHT WITH THE SHORTWAVE PASSED...THE NOSE OF THE 850MB MOISTURE TRANSPORT CENTERED FROM NORTHWEST ONTARIO INTO UPPER MI AND THE FORECAST AREA BECOMING MORE UNDER THE MOISTURE TRANSPORT STREAM ITSELF. THE 23.00Z GFS IS AN OUTLIER HAVING CONVECTION ALL THE WAY SOUTH TOWARDS DUBUQUE WHEREAS ALL OTHER GUIDANCE SUGGESTS ALONG/NORTH I-94 OR EVEN NORTH OF THE FORECAST AREA. LEANED AWAY FROM THE GFS...WHICH STAYS IN GOOD CONTINUITY WITH THE PREVIOUS FORECAST. HIGH CONFIDENCE THAT CONVECTION WILL STAY WELL OFF TO THE NORTHEAST SUNDAY. ANOTHER MONSOON-RELATED SHORTWAVE IS SUGGESTED BY SOME MODELS TO COME ACROSS NORTHERN PORTIONS OF THE FORECAST AREA SUNDAY NIGHT. THE AIRMASS MAY BE CAPPED OFF EVEN TO ELEVATED CONVECTION...BUT WITH THE 22.12Z ECMWF AND 23.00Z GFS DEPICTING SOME CONVECTION WITH THE SHORTWAVE... FELT A 20-30 PERCENT CHANCE IS NEEDED. 23.00Z ECMWF IS DRY FOR SUNDAY NIGHT...WHICH MAY TURN OUT IN REALITY. FOR MONDAY AND BEYOND...MODELS OCCASIONALLY PRODUCE CONVECTION...PARTICULARLY ALONG AND NORTH AND EAST OF I-94 AS SHORTWAVES ROUND THE RIDGE. FROM A CONSENSUS STANDPOINT...THIS YIELDS 20-30 PERCENT CHANCES NEEDED EACH DAY IN THIS AREA. TEMPERATURE DETAILS... FOR SATURDAY...BETWEEN THE CONVECTION AROUND AS WELL AS INDICATIONS OF PLENTY OF CIRRUS...TEMPERATURES ARE LIKELY NOT TO REACH THEIR MAXIMUM POTENTIAL. 850MB TEMPS CLIMBING TO 16C EAST TO 19C WEST WOULD SUPPORT HIGHS IN THE MID TO PERHAPS UPPER 80S...BUT THE AFOREMENTIONED ISSUES LIKELY TO HOLD HIGH TEMPS 5-10 DEGREES COOLER. TEMPERATURES REALLY BEGIN TO HEAT UP ON SUNDAY. COMBINATION OF 925MB TEMPS CLIMBING TO 26-28C AND A BREEZY SOUTHWEST WIND SHOULD EASILY PROPEL HIGHS INTO THE UPPER 80S TO LOW 90S. THE WINDS ARE ALSO GOING TO ADVECT IN HIGHER DEWPOINTS...LIKELY IN THE UPPER 60S TO LOW 70S. HEAT INDICES AS A RESULT TOP OUT IN THE 95 TO 100 RANGE. MONDAY AND TUESDAY BOTH LOOK HOT AS THE WARM AIR SHIFTS EAST OVER THE FORECAST AREA. 925MB TEMPS RISE FURTHER TO 27-29C...PERHAPS EVEN 30C. WITH PLENTY OF SUN...ESPECIALLY SOUTHWEST OF I-94...HIGHS OF 90-95 SHOULD OCCUR. DEWPOINTS MAY NOT CHANGE MUCH COMPARED TO SUNDAY...CAUSING HEAT INDICES TO LIKELY JUMP TO 100-105. THESE DAYS WILL NEED AT LEAST A HEAT ADVISORY. WEDNESDAY AND THURSDAY BECAME A BIT MORE UNCERTAIN WITH THE 23.00Z ECMWF/UKMET. THEY HAVE A SHORTWAVE TROUGH DIGGING INTO NEW ENGLAND WHICH ALLOWS A BACK DOOR COLD FRONT TO COME THROUGH THE FORECAST AREA. 925MB TEMPS COOL TO 24-26C...WHICH WOULD KEEP HIGHS PERHAPS EVEN BELOW 90. ON THE OTHER HAND...THE 23.00Z GFS DOESNT DROP THE COLD FRONT THROUGH...KEEPING 925MB TEMPS UP BETWEEN 28-32C. FOR NOW FOLLOWED A CONSENSUS...WHICH RESULTS IN THESE DAYS BELOW HEAT ADVISORY CONDITIONS. LOWS WILL STAY QUITE WARM DURING THIS STRETCH...LIKELY IN THE LOW TO MID 70S EVERY NIGHT. GIVEN THE UNCERTAINTY WITH WEDNESDAY AND THURSDAY...AND THE VERY MARGINAL CONDITIONS ON SUNDAY...HAVE NOT ISSUED ANY HEAT HAZARDS AT THIS TIME. NOTE THAT MORE HEAT APPEARS TO BE ON THE WAY FOR LABOR DAY WEEKEND. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT) ISSUED AT 1155 PM CDT THU AUG 22 2013 CHALLENGING RIVER VALLEY FOG SETUP FOR KLSE AS A FEW COMPETING FACTORS COULD LEAD TO 1/4SM...OR NOTHING AT ALL. AS HIGH PRESSURE SETTLES TO THE NORTH...SOUTHEASTERLY SURFACE WINDS WILL REMAIN GENERALLY 5 MPH OR LESS. HOWEVER...925 TO 900 MB WINDS ARE EXPECTED TO INCREASE FROM 5 TO 7 MPH THIS EVENING...TO NEARLY 15 TO 20 MPH BY 10Z ACCORDING TO VARIOUS MODEL SOUNDINGS. THIS WIND INCREASE DOES NOT SUPPORT A DENSE FOG EVENT. HOWEVER...THE LATE ARRIVAL OF THIS SPEED MAX COULD ALLOW FOG TO FORM IN THE CHANNEL...THEN TRAP IT BELOW THE INVERSION. ALSO...TRENDS IN THE MODEL SOUNDINGS ARE NOT AS CONSISTENT...AND SOME PREVIOUS RUNS SHOWED A LIGHTER WIND LAYER. ALL IN ALL...WHILE THE WIND ISSUE MAY HURT DENSE FOG CHANCES...NOT SOLD YET THAT IT WILL PRECLUDE DENSE FOG FORMATION. T/TD IS DOWN TO 5 F AS OF 04Z...WITH SFC WINDS REMAINING LIGHT. BOTH FAVORABLE FOR DENSE FOG. KLSE TAF WAS UPDATED BEFORE 03Z TO INCLUDE A PERIOD OF 1/4SM...AND WILL CONTINUE THIS. EXPECT RAPID IMPROVEMENT/CLEARING AROUND 14Z. REST OF THE DAY SHOULD BE VFR...WITH CLOUDS INCREASING OVERNIGHT FRIDAY...AND THE CHANCE FOR SCT SHRA/TS ON SAT. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR WIZ054-055- 061. MN...NONE. IA...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR IAZ008>011- 018-019-029-030. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION.....ZT/RIECK
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
1045 PM PDT SAT AUG 24 2013 NEW AVIATION DISCUSSION .SYNOPSIS... DRY WEATHER WITH NEAR OR SLIGHTLY ABOVE NORMAL TEMPERATURES CAN BE EXPECTED THROUGH SUNDAY. A MOIST AIR MASS FROM THE SOUTH WILL BRING THE SLIGHT CHANCE OF THUNDERSTORMS TO THE LOS ANGELES COUNTY MOUNTAINS AND ANTELOPE VALLEY MONDAY...THEN TO MUCH OF VENTURA AND LOS ANGELES COUNTIES MONDAY NIGHT INTO TUESDAY. AN UPPER LEVEL RIDGE OF HIGH PRESSURE WILL BUILD INTO SOUTHERN CALIFORNIA BY THE MIDDLE TO END OF NEXT WEEK WITH ABOVE NORMAL TEMPERATURES EXPECTED. && .UPDATE... ONSHORE FLOW REMAINS IN PLACE ACROSS THE AREA THIS EVENING ALONG WITH A STUBBORN MARINE LAYER. THE LATEST MODEL SOLUTIONS CONTINUE TO SUGGEST ONSHORE FLOW WEAKENING ACROSS THE AREA ON SUNDAY ALONG WITH INCREASING 500 MB HEIGHTS. WITH THIS MIND...A WARMING TREND REMAINS INTACT ACROSS THE AREA...ESPECIALLY ALONG THE COAST. THE FORECAST WILL HAVE TO BE MONITORED FOR DEVELOPMENT AS MOISTURE IS STARTING TO PUSH INTO THE HIGH DESERTS OF SOUTHERN CALIFORNIA. CURRENTLY...THE PACKAGE HAS NO POPS OR WEATHER FOR THE ANTELOPE VALLEY. HOWEVER...KVCV DEW POINTS HAVE SURGED INTO THE LOWER 50S THIS HOUR...AND KL35 INTO THE 40S. MODEL SOLUTIONS CONTINUE TO KEEP THE BEST MOISTURE AND INSTABILITY SOUTH AND EAST OF THE AREA...BUT DEW POINT DEVELOPMENTS ARE STARTING TO BE PROBLEMATIC. 13-KM RAP MODEL SOLUTION ARE ALSO STARTING HINT AT THE POSSIBILITY OF CONVECTIVE STORM OVER THE EASTERN SAN GABRIEL RANGE. THE NEXT SHIFT WILL BE BRIEFED ACCORDINGLY. && .PREV DISCUSSION... SHORT TERM...12Z MODELS TODAY STARTED TO SHOW A RETURN OF IVO MOISTURE BACK INTO THE EASTERN PART OF OUR FORECAST AREA MONDAY AND ESPECIALLY MONDAY NIGHT INTO TUESDAY. THE GFS AND GEM MODELS HAD SHOWN THIS AT ONE TIME BUT BACKED OFF IN FAVOR OF THE TROF TO THE NORTH USHERING IN MORE DRY AIR FROM THE SOUTHWEST AND PUSHING THE MOISTURE EAST. THE NAM IS THE MOST AGGRESSIVE WITH THE MOISTURE BUT ALL MODELS SHOW A PRETTY DRAMATIC INCREASE FROM THE SOLUTIONS OVER THE LAST COUPLE DAYS. THIS COULD BE JUST A BRIEF FLING WITH WETTER SOLUTIONS BEFORE WAGGING BACK TO A DRIER SOLUTION TONIGHT OR SUNDAY BUT GIVEN THE CONSENSUS IT SEEMS WARRANTED TO RE-INTRODUCE AT LEAST SOME LOW CHANCES OF SHOWERS/STORMS TO LA/VENTURA COUNTIES MONDAY NIGHT INTO TUESDAY. THE NAM ALSO SHOWS RESPECTABLE CAPE AS WELL AS K/LIFTED INDICES DURING THAT TIME, THOUGH MODEL SOUNDINGS ACROSS SOUTHERN LA COUNTY SEEMED TO SUGGEST MORE OF A STRATIFORM PRECIP EVENT (SPRINKLES/LIGHT SHOWERS) RATHER THAN A CONVECTIVE ONE WITH COOLING IN THE LOWER LVLS AND SOME WARMING ALOFT. PWATS INCREASE TO AN IMPRESSIVE 1.75-2" MONDAY NIGHT AND EARLY TUESDAY FOR LA/VENTURA COUNTIES WHILE 850 DEW POINTS INCREASE TO BETWEEN 12-14C. BY TUESDAY AFTERNOON PRECIP THREAT SHOULD BE CONFINED TO THE MOUNTAINS WHERE THE MOST UNSTABLE AIR WILL BE. LONG TERM...A BREAK EXPECTED IN THE MONSOON SURGE ON WEDNESDAY BEFORE MORE MOISTURE ARRIVES STARTING THURSDAY AND CONTINUING INTO THE WEEKEND. ADDED SOME TSTM CHANCES BACK TO THE MOUNTAINS AND ANTELOPE VALLEY BUT LEAVING COASTAL/VALLEY AREAS DRY FOR NOW. AT THE SAME TIME HIGH PRESSURE OVER THE SOUTHWEST IS EXPECTED TO EXPAND OVER CALIFORNIA AND BRING A WARMING TREND TO THE AREA. LOOKING BEYOND THAT THE NEXT TROPICAL CYCLONE IS EXPECTED TO DEVELOP OFF SOUTHERN MEXICO AROUND THE MIDDLE OF NEXT WEEK AND EVENTUALLY BRING YET ANOTHER SURGE OF MOISTURE TO THE AREA LATE NEXT WEEKEND OR EARLY THE FOLLOWING WEEK. SO WE`RE LOOKING AT AN EXTENDED PERIOD OF POTENTIALLY WARM AND MUGGY CONDITIONS, WHICH IS TO BE EXPECTED THIS TIME OF YEAR. && .AVIATION... 25/0545Z SHALLOW 900 FOOT DEEP MARINE LAYER COMBINED WITH A WEAK EDDY WILL BRING LIFR TO IFR CIGS TO THE COASTAL TAF SITES OVERNIGHT. ARRIVAL TIMING COULD BE AS MUCH AS TWO HOURS OFF BUT BETTER CONFIDENCE IN CLEARING TIMES. KLAX...GOOD CONFIDENCE IN TAF CIGS COULD BOUNCE FROM LIFR TO IFR BETWEEN 07Z-13Z. NOTE: PREVAILING 1/4SM VIS IS A RESULT OF THE OBSERVATION DECKS ELEVATED TOWER LOCATION. TAF VIS REFLECTS THE ACTUAL SFC VIS. KBUR...HIGH CONFIDENCE IN CAVU TAF. && .LOX WATCHES/WARNINGS/ADVISORIES... SMALL CRAFT ADVISORY (SEE LAXMWWLOX). && $$ PUBLIC...HALL/MW AVIATION...HALL SYNOPSIS...SIRARD WWW.WEATHER.GOV/LOSANGELES
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
918 PM PDT SAT AUG 24 2013 .SYNOPSIS... DRY WEATHER WITH NEAR OR SLIGHTLY ABOVE NORMAL TEMPERATURES CAN BE EXPECTED THROUGH SUNDAY. A MOIST AIR MASS FROM THE SOUTH WILL BRING THE SLIGHT CHANCE OF THUNDERSTORMS TO THE LOS ANGELES COUNTY MOUNTAINS AND ANTELOPE VALLEY MONDAY...THEN TO MUCH OF VENTURA AND LOS ANGELES COUNTIES MONDAY NIGHT INTO TUESDAY. AN UPPER LEVEL RIDGE OF HIGH PRESSURE WILL BUILD INTO SOUTHERN CALIFORNIA BY THE MIDDLE TO END OF NEXT WEEK WITH ABOVE NORMAL TEMPERATURES EXPECTED. && .UPDATE... ONSHORE FLOW REMAINS IN PLACE ACROSS THE AREA THIS EVENING ALONG WITH A STUBBORN MARINE LAYER. THE LATEST MODEL SOLUTIONS CONTINUE TO SUGGEST ONSHORE FLOW WEAKENING ACROSS THE AREA ON SUNDAY ALONG WITH INCREASING 500 MB HEIGHTS. WITH THIS MIND...A WARMING TREND REMAINS INTACT ACROSS THE AREA...ESPECIALLY ALONG THE COAST. THE FORECAST WILL HAVE TO BE MONITORED FOR DEVELOPMENT AS MOISTURE IS STARTING TO PUSH INTO THE HIGH DESERTS OF SOUTHERN CALIFORNIA. CURRENTLY...THE PACKAGE HAS NO POPS OR WEATHER FOR THE ANTELOPE VALLEY. HOWEVER...KVCV DEW POINTS HAVE SURGED INTO THE LOWER 50S THIS HOUR...AND KL35 INTO THE 40S. MODEL SOLUTIONS CONTINUE TO KEEP THE BEST MOISTURE AND INSTABILITY SOUTH AND EAST OF THE AREA...BUT DEW POINT DEVELOPMENTS ARE STARTING TO BE PROBLEMATIC. 13-KM RAP MODEL SOLUTION ARE ALSO STARTING HINT AT THE POSSIBILITY OF CONVECTIVE STORM OVER THE EASTERN SAN GABRIEL RANGE. THE NEXT SHIFT WILL BE BRIEFED ACCORDINGLY. && .PREV DISCUSSION... SHORT TERM...12Z MODELS TODAY STARTED TO SHOW A RETURN OF IVO MOISTURE BACK INTO THE EASTERN PART OF OUR FORECAST AREA MONDAY AND ESPECIALLY MONDAY NIGHT INTO TUESDAY. THE GFS AND GEM MODELS HAD SHOWN THIS AT ONE TIME BUT BACKED OFF IN FAVOR OF THE TROF TO THE NORTH USHERING IN MORE DRY AIR FROM THE SOUTHWEST AND PUSHING THE MOISTURE EAST. THE NAM IS THE MOST AGGRESSIVE WITH THE MOISTURE BUT ALL MODELS SHOW A PRETTY DRAMATIC INCREASE FROM THE SOLUTIONS OVER THE LAST COUPLE DAYS. THIS COULD BE JUST A BRIEF FLING WITH WETTER SOLUTIONS BEFORE WAGGING BACK TO A DRIER SOLUTION TONIGHT OR SUNDAY BUT GIVEN THE CONSENSUS IT SEEMS WARRANTED TO RE-INTRODUCE AT LEAST SOME LOW CHANCES OF SHOWERS/STORMS TO LA/VENTURA COUNTIES MONDAY NIGHT INTO TUESDAY. THE NAM ALSO SHOWS RESPECTABLE CAPE AS WELL AS K/LIFTED INDICES DURING THAT TIME, THOUGH MODEL SOUNDINGS ACROSS SOUTHERN LA COUNTY SEEMED TO SUGGEST MORE OF A STRATIFORM PRECIP EVENT (SPRINKLES/LIGHT SHOWERS) RATHER THAN A CONVECTIVE ONE WITH COOLING IN THE LOWER LVLS AND SOME WARMING ALOFT. PWATS INCREASE TO AN IMPRESSIVE 1.75-2" MONDAY NIGHT AND EARLY TUESDAY FOR LA/VENTURA COUNTIES WHILE 850 DEW POINTS INCREASE TO BETWEEN 12-14C. BY TUESDAY AFTERNOON PRECIP THREAT SHOULD BE CONFINED TO THE MOUNTAINS WHERE THE MOST UNSTABLE AIR WILL BE. LONG TERM...A BREAK EXPECTED IN THE MONSOON SURGE ON WEDNESDAY BEFORE MORE MOISTURE ARRIVES STARTING THURSDAY AND CONTINUING INTO THE WEEKEND. ADDED SOME TSTORM CHANCES BACK TO THE MOUNTAINS AND ANTELOPE VALLEY BUT LEAVING COASTAL/VALLEY AREAS DRY FOR NOW. AT THE SAME TIME HIGH PRESSURE OVER THE SOUTHWEST IS EXPECTED TO EXPAND OVER CALIFORNIA AND BRING A WARMING TREND TO THE AREA. LOOKING BEYOND THAT THE NEXT TROPICAL CYCLONE IS EXPECTED TO DEVELOP OFF SOUTHERN MEXICO AROUND THE MIDDLE OF NEXT WEEK AND EVENTUALLY BRING YET ANOTHER SURGE OF MOISTURE TO THE AREA LATE NEXT WEEKEND OR EARLY THE FOLLOWING WEEK. SO WE`RE LOOKING AT AN EXTENDED PERIOD OF POTENTIALLY WARM AND MUGGY CONDITIONS, WHICH IS TO BE EXPECTED THIS TIME OF YEAR. && .AVIATION...25/0000Z. AT COASTAL TERMINALS...LIFR TO IFR CONDITIONS WILL REDEVELOP THROUGH 11Z...POSSIBLY LOWERING ONE CATEGORY BETWEEN 08Z AND 15Z ESPECIALLY NORTH OF POINT CONCEPTION. VFR CONDITIONS SHOULD REDEVELOP BETWEEN 16Z AND 18Z. THERE IS A SLIGHT CHANCE THAT SUB-VFR CONDITIONS COULD LINGER BEYOND 18Z. KLAX...IFR CONDITIONS WILL LIKELY PERSIST THROUGH AT LEAST 04Z...THEN LOWER TO LIFR BETWEEN 04Z AND 08Z. THERE IS A 30 PERCENT CHANCE OF VLIFR CONDITIONS BETWEEN 08Z AND 15Z. VFR CONDITIONS SHOULD REDEVELOP BETWEEN 16Z AND 18Z. THERE IS A 20 PERCENT CHANCE THAT SUB-VFR CONDITIONS LINGERING BEYOND 18Z. KBUR...VFR CONDITIONS ARE EXPECTED THROUGHOUT THE PERIOD. && .LOX WATCHES/WARNINGS/ADVISORIES... SMALL CRAFT ADVISORY (SEE LAXMWWLOX). && $$ PUBLIC...HALL/MW AVIATION...HALL SYNOPSIS...SIRARD WWW.WEATHER.GOV/LOSANGELES
AREA FORECAST DISCUSSION
NWS GOODLAND KS
254 AM MDT SUN AUG 25 2013 .SHORT TERM...(TODAY THROUGH TUESDAY NIGHT) ISSUED AT 254 AM MDT SUN AUG 25 2013 LITTLE IS GOING TO CHANGE REGARDING THE THE LARGE SCALE PATTERN ACROSS THE CENTRAL US...WITH HOT/DRY CONDITIONS EXPECTED OVER OUR CWA. LARGE H5 RIDGE REMAIN IN PLACE OVER THE CENTRAL CONUS...WITH LATEST RAP ANALYSIS SHOWS 595DM CENTER ACROSS KS/MO STATE LINE. GFS/NAM SHOW HEIGHTS CONTINUING TO RISE THROUGH THE DAY WITH 597-598DM CENTER BY 00Z THIS AFTERNOON. WITH DRY/STABLE AIR MASS IN PLACE PRIMARY CONCERN WILL CONTINUE TO BE HOT TEMPERATURES AND MARGINAL FIRE WEATHER CONDITIONS IN THE WEST. STRONG LEE TROUGH WILL REMAIN IN PLACE THROUGH MONDAY...WITH STRONG SOUTHERLY PRESSURE GRADIENT OVER OUR CWA. BREEZY TO WINDY CONDITIONS ARE EXPECTED TODAY THROUGH MONDAY...WITH LATEST GUIDANCE BEGINNING TO SHOW WINDY CONDITIONS FURTHER WEST WHERE LOWER RH VALUES WILL BE. AT THIS POINT...IT APPEARS WE WILL BE JUST OUTSIDE OF RFW CRITERIA FOR RH...THOUGH I COULDNT RULE OUT A FEW WESTERN LOCATIONS FALLING JUST WITHIN LOCAL CRITERIA. I AM NOT PLANNING ON ISSUING A WARNING AT THIS TIME DUE TO THE MARGINAL AND ISOLATED NATURE OF THESE CONDITIONS. THERE IS ALSO A QUESTION REGARDING FUELS...WITH ISOLATED PARTS OF OUR CWA HAVING RECEIVED QUITE A BIT OF RAINFALL SINCE LATE JUNE DESPITE THE MAJORITY OF THE AREA REMAINING IN DROUGHT. SATELLITE DERIVED GREENNESS PRODUCTS SHOW PREDOMINANTLY GREEN FUELS OVER PARTS OF THE TRI-STATE AREA...THOUGH THERE ARE PARTS OF MANY COUNTIES THAT FALL BELOW NORMAL GREENNESS LEVELS. IF CONDITIONS WERE LESS MARGINAL...THE STATUS OF FUELS MIGHT STILL PREEMPT ISSUANCE OF RFW FOR PARTS OF OUR CWA. REGARDING HIGH/LOW TEMPS...I USED BIASES FROM SUN AS THE BASIS FOR THE FORECAST THROUGH TUE WITH VERY SIMILAR AIR MASS IN PLACE EACH DAY. I ALSO TRENDED LOW TEMPS UP FROM PREVIOUS FORECAST WITH BREEZY WINDS LIKELY IMPACTING RADIATIONAL COOLING EACH NIGHT. FORECAST IS STILL CALLING FOR UPPER 90S/LOW 100S EACH AFTERNOON..AND BY MON/TUE I WOULDNT BE SURPRISED IF WE SAW A FEW LOCATIONS COME WITHIN A FEW DEGREES OF RECORD HIGHS. .LONG TERM...(WEDNESDAY THROUGH SATURDAY) ISSUED AT 254 AM MDT SUN AUG 25 2013 MUCH OF THE SAME FOR THE SECOND HALF OF THIS WEEK WITH HOT AND DRY CONDITIONS CONTINUING. A BROAD H5 RIDGE CENTERED OVER KANSAS WILL BE WELL-ESTABLISHED BY MID-WEEK. THIS RIDGE WILL GRADUALLY BUILD WEST OVER THE REST OF THE WEEK...KEEPING THE SENSIBLE WX FAIRLY BENIGN. THE ONLY INTERESTING FEATURE IS A WEAK VORT MAX THAT MAY MOVE ACROSS EASTERN COLORADO INTO WESTERN KANSAS LATE THURSDAY. WHILE THERE WILL BE SOME UPPER-LEVEL MOISTURE...SOUNDINGS APPEAR TOO STABLE TO SUPPORT WIDESPREAD STORMS. THE OPERATIONAL GFS PRINTS OUT SOME QPF IN WESTERN KANSAS FROM THIS...AS WELL AS JUST ONE OF THE TWELVE ENSEMBLE PERTURBATIONS...SO HAVE LITTLE CONFIDENCE IN ANY PRECIP BEING REALIZED. RIDGE CONTINUES DRIFTING WESTWARD OVER THE WEEKEND WHILE AN UPPER LOW MOVING INTO THE PACIFIC NORTHWEST MAY HELP TO WEAKEN THE RIDGE LATE IN THE WEEKEND. FOR NOW...NO PRECIP CHANCES THROUGH SATURDAY AFTERNOON. FOR TEMPS...ALL GUIDANCE CONTINUES TO TREND WARMER FOR THE PERIOD WITH 850MB TEMPS IN THE LOW 30S C. TEMPS WILL BE NEARLY THE SAME EVERY DAY...HIGHS IN THE MID TO UPPER 90S AND LOWS IN THE MID 60S TO LOW 70S. HIGHS ARE NOT EXPECTED TO BE RECORD BREAKING...BUT A FEW STATIONS COULD APPROACH RECORD HIGHS ANY DAY OF THE EXTENDED. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 1154 PM MDT SAT AUG 24 2013 VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD AT MCK AND GLD. SOUTH WINDS WILL INCREASE AND BECOME GUSTY DURING THE DAY ON SUNDAY BETWEEN 14Z AND 23Z AND WILL LOSE THE GUSTS FOLLOWING SUNSET. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...DR LONG TERM...JJM AVIATION...LOCKHART
AREA FORECAST DISCUSSION
NWS DULUTH MN
349 AM CDT SUN AUG 25 2013 .SHORT TERM...THROUGH EARLY MONDAY EVENING. HOT AND HUMID CONDITIONS WILL COVER MUCH OF THE NORTHLAND TODAY. THE LARGE UPPER HIGH OVER THE CENTRAL CONUS WILL REMAIN THROUGH THE SHORT TERM...WITH A COUPLE DIFFERENT FEATURES MOVING THROUGH BRINGING A THREAT FOR SHOWERS/STORMS. AS OF 0830Z...A FEW THUNDERSTORMS WERE OCCURRING OVER FAR NORTHERN MINNESOTA DUE TO A PASSING WAVE AND WAA WITH SOUTHWESTERLY LLJ. KDLH`S VWP SHOWED 35 KT AT 925MB WITH WEST WINDS AT 850MB OF 50 KT. STRONG THUNDERSTORMS WERE OCCURRING OVER EASTERN NORTH DAKOTA IN AN AREA OF LOW LEVEL CONVERGENCE ALONG A WEAK FRONTAL BOUNDARY. THE AIRMASS IS PLENTY UNSTABLE THIS MORNING WITH MUCAPES OF 1000-2000J/KG AND MLCAPES OF 500-1500J/KG. WARM LOW-MID LEVEL TEMPS COVERED THE CWA...WITH THE MODELS SHOWING 700MB TEMPS OF +10 TO +12C. THE 00Z KINL SOUNDING HAD +11C AT 700MB. WE EXPECT THE NORTHERN MINNESOTA SHOWERS/STORMS TO CONTINUE EAST EARLY THIS MORNING...WITH SOUTHWARD DEVELOPMENT LOOKING LESS LIKELY. THE LOW LEVEL CONVERGENT AREA AS FORECAST BY THE RAP AT 925MB...MAY ALLOW FOR SOME ADDITIONAL DEVELOPMENT OVER PORTIONS OF OUR WEST/SOUTHWEST PRIOR TO 12Z...BUT MORE LIKELY AFTER THAT TIME. THERE WILL BE A BATTLE BETWEEN THE LIFT FROM THE APPROACHING TROUGH AND THE WARM MID LEVEL TEMPS TODAY. WE DO KEEP SOME LOW POPS OVER CENTRAL PORTIONS OF THE CWA...THEN INCREASE FURTHER LATER THIS AFTERNOON WITH MAX HEATING...THE LOW LEVEL TROUGH AND PERHAPS A WEAK WAVE ALL CONTRIBUTING TO LIFT. THE STORMS COULD BE SEVERE OVER THE SOUTHERN HALF OF THE NORTHLAND THIS AFTERNOON INTO TONIGHT. WE STILL EXPECT HIGHS TO REACH THE LOWER TO MIDDLE NINETIES OVER MUCH OF THE NORTHLAND. DULUTH MAY BREAK IT`S RECORD HIGH FOR THE DATE...WHICH IS 90...AND INTERNATIONAL FALLS WILL BE CLOSE WITH IT`S RECORD HIGH TODAY OF 92. IT WILL BE HUMID WITH DEWPOINTS IN THE UPPER SIXTIES TO LOWER SEVENTIES. WE KEPT THE HEAT ADVISORY THE SAME. AREAS AROUND LAKE SUPERIOR...EXCEPT FOR PERHAPS UP INTO COASTAL COOK COUNTY...WILL ALSO BE HOT TODAY DUE TO OFFSHORE WINDS. MONDAY WILL REMAIN HOT WITH HIGHS FROM THE UPPER EIGHTIES TO LOWER NINETIES. AREAS ALONG LAKE SUPERIOR WILL BE COOLER THOUGH...AS AN ONSHORE FLOW DEVELOPS DUE TO LOW PRESSURE OUT TO THE WEST AND A WEAK HIGH TO THE EAST. A WARM FRONT WILL BE DRAPED FROM WEST TO EAST ACROSS THE NORTHLAND. WE INTRODUCED SOME POPS ALONG THIS FEATURE OVER ALL BUT FAR NORTHERN MINNESOTA ON MONDAY. CONVERGENCE IS WEAK...BUT WE CAN`T RULE OUT SOME THUNDERSTORM DEVELOPMENT WITH PEAK HEATING. .LONG TERM...MONDAY NIGHT THROUGH SUNDAY. A LARGE SFC/MID LVL RIDGE WILL PREVAIL OVER THE SRN PLAINS THROUGH THE WEEK WITH UNUSUALLY HOT AND MUGGY WEATHER EXPECTED ACROSS THE NORTHLAND. THE HEAT WILL BE TEMPERED BRIEFLY BY THE PASSAGE OF A FRONTAL SYSTEM MON NIGHT AND EARLY TUESDAY. THIS WILL BE THE BEST CHANCE FOR MUCH NEEDED PRECIP ACROSS THE CTRL/SRN CWA. HOWEVER...THE PRESENCE OF THE ANOMALOUS RIDGE AT MID LVLS WITH AN ASSOCIATED MID LVL WARM LAYER MAKES THE CONVECTIVE OPPORTUNITIES QUESTIONABLE. MOST LIKELY AREA WILL BE NRN MN ZONES AHEAD OF WARM FRONTAL BDRY MONDAY NIGHT AND ON NRN FRINGES OF NORTHWARD ADVECTING MID LVL CAP. SFC COLD FRONT WILL PASS THROUGH TUESDAY HOWEVER EXTENSIVE CIN IS EXPECTED BY EARLY AFTN SO POPS LOWERED. HIGH PRESSURE IS EXPECTED TO PASS ACROSS THE AREA WED/WED NIGHT. A TEMPORARY REDUCTION IN HUMIDITY SHOULD OCCUR BEFORE SFC HIGH MOVES EAST THURSDAY. HEAT/HUMIDITY INCREASE LATE WEEK INTO WEEKEND AS WARM ADVECTION RESUMES. LOW POPS LATE WEEK AND INTO WEEKEND AS UPPER JET REMAINS NORTH OF CWA AND MAIN CONVECTION CHANCES ARE POSITIONED NORTH AND WEST OF CWA. && .AVIATION...06Z TAF ISSUANCE. VFR CONDITIONS WILL PREVAIL MOST OF THE FCST PERIOD EXCEPT IN THE NRN TIER OF MN WHERE LOCAL MVFR/IFR MAY OCCUR IN LOWER CLOUD DEVELOPMENT AND HEAVIER STORMS EARLY THIS MORNING. A WEAK SFC BDRY WILL TRY TO PUSH SOUTH ACROSS THE AREA TODAY. MID LVL WARMTH SHOULD MAKE CONVECTION TOUGH TO DEVELOP. AMENDMENTS MAY BE REQUIRED GIVEN UNCERTAINTY OF CONVECTIVE DEVELOPMENT. LLWS AT KBRD/KHYR AS 45/50KT LLJ TRANSLATES EAST THROUGH 12Z. && .POINT TEMPS/POPS... DLH 92 69 89 68 / 40 50 20 50 INL 87 61 88 67 / 20 10 10 60 BRD 96 69 94 72 / 30 50 20 40 HYR 94 71 92 71 / 40 60 20 50 ASX 93 69 85 68 / 40 50 20 50 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...HEAT ADVISORY FROM 11 AM THIS MORNING TO 9 PM CDT MONDAY FOR MNZ033>038. WI...HEAT ADVISORY FROM 11 AM THIS MORNING TO 9 PM CDT MONDAY FOR WIZ001>004-006>009. LS...NONE. && $$ SHORT TERM...MELDE LONG TERM....CANNON AVIATION...CLC
AREA FORECAST DISCUSSION
NWS BISMARCK ND
111 PM CDT FRI AUG 23 2013 .UPDATE... ISSUED AT 105 PM CDT FRI AUG 23 2013 EARLY THIS AFTERNOON...WARM FRONT ACROSS EASTERN MONTANA. EAST OF THIS TROUGH A GOOD SOUTHEAST FLOW WAS BRING INCREASING DEW POINTS INTO THE REGION. SOUNDING FORECAST SHOWS CENTRAL AND EAST WELL CAPPED THIS AFTERNOON. THE WEST BECOMES UNCAPPED LATE IN THE DAY. SO REMOVED MENTION OF THUNDERSTORMS THROUGH THE AFTERNOON. EXPECT THE START OF CONVECTION THIS EVENING. OTHER ASPECTS OF THE FORECAST LOOK GOOD. UPDATE ISSUED AT 937 AM CDT FRI AUG 23 2013 WARM H500 RIDGE REMAINS OVER THE NORTHERN PLAINS TODAY. WITHIN THE RIDGE THERE IS A WEAK VORT LOBE MOVING THROUGH WHICH...AIDED BY THE DIURNAL LOW LEVEL JET...(30 KTS ON 12Z KBIS SOUNDING) SPONSORING SOME WEAK CONVECTION CROSS THE SOUTH CENTRAL THIS MORNING. CONVECTION EXPECTED TO DIMINISH AS THE LOW LEVEL FEATURES MIX OUT THIS AM. THEN SYNOPTIC SCALE FORCING WILL PREVAIL THIS AFTERNOON AND EVENING AS WARM FRONT IN EASTERN MONTANA MOVES EAST. THE WARM FRONT WILL BE THE FOCUS FOR SCATTERED THUNDERSTORMS SOUTHWEST AND WEST CENTRAL THIS AFTERNOON/EVENING. MADE SOME CHANGES TO CLOUDS AND POPS THIS AM TO FOCUS ON THE ON GONG CONVECTION. OTHERWISE NO OTHER CHANGES. UPDATE ISSUED AT 643 AM CDT FRI AUG 23 2013 WEAK SHORTWAVE OVER SOUTHWEST NORTH DAKOTA IS PRODUCING ISOLATED SHOWERS AND A FEW RUMBLES OF THUNDER OVER CENTRAL NORTH DAKOTA. HAVE UPDATED POPS TO LATEST RADAR IMAGERY AND TRANSLATED THIS NORTH AND EAST THROUGH MID MORNING. ALSO KEPT ISOLATED THUNDER EXTENDING BACK INTO THE SOUTHWEST AS ANOTHER CELL HAD DEVELOPED OVER THE FAR SOUTHWEST. OTHERWISE NO CHANGES TO THE CURRENT FORECAST. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 250 AM CDT FRI AUG 23 2013 MAIN FORECAST CHALLENGE TODAY/TONIGHT WILL BE THUNDERSTORM POTENTIAL AND AREAL COVERAGE. LATEST WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL HIGH LOCATED OVER SOUTHWEST KANSAS WITH RIDGING NORTH INTO EASTERN MONTANA. LOW PRESSURE CIRCULATING OVER WESTERN OREGON IS EJECTING SEVERAL SHORTWAVES INTO AND OVER THE RIDGE . THE 00Z MODEL GUIDANCE AND HIGH RESOLUTION MODELS ALL OFFER DIFFERENT SCENARIOS FOR CONVECTION TODAY INTO FRIDAY NIGHT. HIGHEST CONFIDENCE IS IN THE NEAR TERM PERIOD WITH AN AREA OF SHOWERS AND THUNDERSTORMS IN SOUTHEAST MONTANA MARCHING TOWARD SOUTHWEST NORTH DAKOTA. THE LATEST HRRR HAS INITIALIZED WELL WITH THIS AREA AND WILL FOLLOW IT FOR THE MORNING HOURS. ESSENTIALLY THIS AREA IS FORECAST TO SLIDE ACROSS SOUTHWEST NORTH DAKOTA...THEN WEAKEN AND FALL APART AS IT APPROACHES SOUTH CENTRAL NORTH DAKOTA LATER THIS MORNING. THE SHORTWAVE CAUSING THIS PRECIPITATION IS SEEN OVER FAR SOUTHERN MONTANA NEAR AND ALONG THE WYOMING BORDER. IT IS FORECAST TO CONTINUE TO PUSH INTO SOUTHERN NORTH DAKOTA THIS AFTERNOON. VARIOUS CAPE/CIN SOUNDINGS PROFILES PER NAM/GFS ARGUES FOR A MODEL BLEND AT THIS TIME...AS IT IS UNCLEAR HOW MUCH OF A CAP REMAINS THIS AFTERNOON INTO FRIDAY NIGHT. IT SEEMS REASONABLE THAT WITH A LEE SIDE TROUGH IN EASTERN MONTANA TODAY...THIS WOULD BE THE AREA TO WATCH FOR THE MOST INTENSE THUNDERSTORMS TO DEVELOP THIS AFTERNOON...WITH CLOSE MONITORING THROUGH THE EVENING HOURS AS THEY MOVE NORTHEAST INTO WESTERN NORTH DAKOTA. CURRENT THINKING IS ANY CONVECTION IN CENTRAL NORTH DAKOTA THIS AFTERNOON SHOULD REMAIN ISOLATED IN NATURE. H85 TEMPS WILL BE RISING AGAIN IN THE WEST WITH STRONG WARM AIR ADVECTION RESULTING IN HIGHS IN THE LOW TO MID 90S. FOR FRIDAY NIGHT...IT APPEARS THE MAIN FOCUS AND THREAT FOR SHOWERS AND THUNDERSTORMS WILL RESIDE OVER NORTHERN NORTH DAKOTA. A SHORTWAVE IS FORECAST TO MOVE ACROSS NORTHEAST MONTANA BY 06Z SATURDAY...AND INTO SOUTHEASTERN SASKATCHEWAN BY 12Z SATURDAY. BEST FORCING IS IN THE NORTH AND HAVE HIGH CHANCE POPS FORECAST OVERNIGHT WITH SLIGHT CHANCE ELSEWHERE. OVERNIGHT LOWS WILL BE IN THE 60S. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 250 AM CDT FRI AUG 23 2013 MAIN FORECAST ISSUES IN THE LONG TERM WILL BE DAYTIME HIGH TEMPERATURES...POSSIBLE HEAT ADVISORY HIGHLIGHTS AND PERIODIC THUNDERSTORM CHANCES. THERE IS A CONTINUED AGREEMENT IN THE MEAN UPPER LEVEL FLOW WHICH FEATURES A STRONG RIDGE OVER THE CENTRAL U.S. THIS WILL RESULT IN TEMPERATURES WELL ABOVE NORMAL THROUGH THE EXTENDED PERIOD ACROSS WESTERN AND CENTRAL NORTH DAKOTA. DAYTIME HIGHS FROM THE UPPER 80S TO LOWER 90S NORTH AND LOWER TO MID 90S SOUTH ARE EXPECTED...WITH SOME UPPER 90S AND LOWER 100 DEGREE READINGS QUITE POSSIBLE ACROSS THE SOUTH. WITH DEWPOINTS GENERALLY IN THE 60S EACH DAY...AFTERNOON HEAT INDICES WILL LIKELY APPROACH 100 DEGREES EACH DAY...ESPECIALLY ACROSS THE SOUTH. EVEN IN THE SHORT TERM MODELS ARE HAVING A HARD TIME RESOLVING SHORTWAVES TRANSLATING THROUGH THE BROAD SOUTHWEST FLOW FROM THE WESTERN UPPER LOW INTO THE NORTHERN PLAINS AND SOUTHERN CANADA. THEREFORE A MODEL BLEND WAS UTILIZED FOR POPS THROUGH THE PERIOD. MODELS ARE TRYING TO DEVELOP CONVECTION ON SATURDAY AND SATURDAY NIGHT AS THERE WILL BE A SURFACE TROUGH TRACKING SLOWLY EAST ACROSS THE AREA THAT IS PROGGED TO BE OVER CENTRAL NORTH DAKOTA BY 00 UTC SUNDAY...WITH SHORTWAVE ENERGY MOVING INTO WESTERN NORTH DAKOTA. WE WILL HAVE ABUNDANT CAPE OVER THE AREA SATURDAY AFTERNOON BUT WILL LIKELY REMAIN CAPPED UNTIL SHORTWAVE ENERGY ARRIVES LATE IN THE DAY. THUS THE BEST THUNDERSTORM CHANCES ON SATURDAY ARE EXPECTED TO BE IN THE EVENING AND OVERNIGHT. SOME OF THESE COULD BE STRONG TO SEVERE. THEREAFTER...THUNDERSTORM CHANCES CANNOT BE RULED OUT EACH DAY AS THE LOWER ATMOSPHERE REMAINS MOIST AND UNSTABLE WITH SHORTWAVE ENERGY CONTINUING TO TRAVERSE THE AREA. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 105 PM CDT FRI AUG 23 2013 AT 1 PM CDT...A WARM FRONT ACROSS EASTERN MONTANA IS FORECAST TO MOVE INTO WESTERN NORTH DAKOTA TONIGHT. THE FRONT WILL BE THE FOCUS FOR SCATTERED SHOWERS AND THUNDERSTORMS. AHEAD OF THIS FRONT SOUTHEAST FLOW WILL BRING 15 TO 25 KT WINDS INTO CENTRAL NORTH DAKOTA. THIS WINDS WILL DIMINISH TO LESS THAN 10 KTS TONIGHT AND SATURDAY. DUE TO UNCERTAINTY IN THE TIMING AND AREA OF WIDELY SCATTERED THUNDERSTORMS...HANDLED THE THREAT USING THE VICINITY OPTION FOR THUNDERSTORMS...MAINLY BETWEEN 02Z-12Z TONIGHT. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...WAA SHORT TERM...KS LONG TERM...TWH AVIATION...WAA
AREA FORECAST DISCUSSION
NWS BISMARCK ND
953 AM CDT FRI AUG 23 2013 .UPDATE... ISSUED AT 937 AM CDT FRI AUG 23 2013 WARM H500 RIDGE REMAINS OVER THE NORTHERN PLAINS TODAY. WITHIN THE RIDGE THERE IS A WEAK VORT LOBE MOVING THROUGH WHICH...AIDED BY THE DIURNAL LOW LEVEL JET...(30 KTS ON 12Z KBIS SOUNDING) SPONSORING SOME WEAK CONVECTION CROSS THE SOUTH CENTRAL THIS MORNING. CONVECTION EXPECTED TO DIMINISH AS THE LOW LEVEL FEATURES MIX OUT THIS AM. THEN SYNOPTIC SCALE FORCING WILL PREVAIL THIS AFTERNOON AND EVENING AS WARM FRONT IN EASTERN MONTANA MOVES EAST. THE WARM FRONT WILL BE THE FOCUS FOR SCATTERED THUNDERSTORMS SOUTHWEST AND WEST CENTRAL THIS AFTERNOON/EVENING. MADE SOME CHANGES TO CLOUDS AND POPS THIS AM TO FOCUS ON THE ON GONG CONVECTION. OTHERWISE NO OTHER CHANGES. UPDATE ISSUED AT 643 AM CDT FRI AUG 23 2013 WEAK SHORTWAVE OVER SOUTHWEST NORTH DAKOTA IS PRODUCING ISOLATED SHOWERS AND A FEW RUMBLES OF THUNDER OVER CENTRAL NORTH DAKOTA. HAVE UPDATED POPS TO LATEST RADAR IMAGERY AND TRANSLATED THIS NORTH AND EAST THROUGH MID MORNING. ALSO KEPT ISOLATED THUNDER EXTENDING BACK INTO THE SOUTHWEST AS ANOTHER CELL HAD DEVELOPED OVER THE FAR SOUTHWEST. OTHERWISE NO CHANGES TO THE CURRENT FORECAST. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 250 AM CDT FRI AUG 23 2013 MAIN FORECAST CHALLENGE TODAY/TONIGHT WILL BE THUNDERSTORM POTENTIAL AND AREAL COVERAGE. LATEST WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL HIGH LOCATED OVER SOUTHWEST KANSAS WITH RIDGING NORTH INTO EASTERN MONTANA. LOW PRESSURE CIRCULATING OVER WESTERN OREGON IS EJECTING SEVERAL SHORTWAVES INTO AND OVER THE RIDGE . THE 00Z MODEL GUIDANCE AND HIGH RESOLUTION MODELS ALL OFFER DIFFERENT SCENARIOS FOR CONVECTION TODAY INTO FRIDAY NIGHT. HIGHEST CONFIDENCE IS IN THE NEAR TERM PERIOD WITH AN AREA OF SHOWERS AND THUNDERSTORMS IN SOUTHEAST MONTANA MARCHING TOWARD SOUTHWEST NORTH DAKOTA. THE LATEST HRRR HAS INITIALIZED WELL WITH THIS AREA AND WILL FOLLOW IT FOR THE MORNING HOURS. ESSENTIALLY THIS AREA IS FORECAST TO SLIDE ACROSS SOUTHWEST NORTH DAKOTA...THEN WEAKEN AND FALL APART AS IT APPROACHES SOUTH CENTRAL NORTH DAKOTA LATER THIS MORNING. THE SHORTWAVE CAUSING THIS PRECIPITATION IS SEEN OVER FAR SOUTHERN MONTANA NEAR AND ALONG THE WYOMING BORDER. IT IS FORECAST TO CONTINUE TO PUSH INTO SOUTHERN NORTH DAKOTA THIS AFTERNOON. VARIOUS CAPE/CIN SOUNDINGS PROFILES PER NAM/GFS ARGUES FOR A MODEL BLEND AT THIS TIME...AS IT IS UNCLEAR HOW MUCH OF A CAP REMAINS THIS AFTERNOON INTO FRIDAY NIGHT. IT SEEMS REASONABLE THAT WITH A LEE SIDE TROUGH IN EASTERN MONTANA TODAY...THIS WOULD BE THE AREA TO WATCH FOR THE MOST INTENSE THUNDERSTORMS TO DEVELOP THIS AFTERNOON...WITH CLOSE MONITORING THROUGH THE EVENING HOURS AS THEY MOVE NORTHEAST INTO WESTERN NORTH DAKOTA. CURRENT THINKING IS ANY CONVECTION IN CENTRAL NORTH DAKOTA THIS AFTERNOON SHOULD REMAIN ISOLATED IN NATURE. H85 TEMPS WILL BE RISING AGAIN IN THE WEST WITH STRONG WARM AIR ADVECTION RESULTING IN HIGHS IN THE LOW TO MID 90S. FOR FRIDAY NIGHT...IT APPEARS THE MAIN FOCUS AND THREAT FOR SHOWERS AND THUNDERSTORMS WILL RESIDE OVER NORTHERN NORTH DAKOTA. A SHORTWAVE IS FORECAST TO MOVE ACROSS NORTHEAST MONTANA BY 06Z SATURDAY...AND INTO SOUTHEASTERN SASKATCHEWAN BY 12Z SATURDAY. BEST FORCING IS IN THE NORTH AND HAVE HIGH CHANCE POPS FORECAST OVERNIGHT WITH SLIGHT CHANCE ELSEWHERE. OVERNIGHT LOWS WILL BE IN THE 60S. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 250 AM CDT FRI AUG 23 2013 MAIN FORECAST ISSUES IN THE LONG TERM WILL BE DAYTIME HIGH TEMPERATURES...POSSIBLE HEAT ADVISORY HIGHLIGHTS AND PERIODIC THUNDERSTORM CHANCES. THERE IS A CONTINUED AGREEMENT IN THE MEAN UPPER LEVEL FLOW WHICH FEATURES A STRONG RIDGE OVER THE CENTRAL U.S. THIS WILL RESULT IN TEMPERATURES WELL ABOVE NORMAL THROUGH THE EXTENDED PERIOD ACROSS WESTERN AND CENTRAL NORTH DAKOTA. DAYTIME HIGHS FROM THE UPPER 80S TO LOWER 90S NORTH AND LOWER TO MID 90S SOUTH ARE EXPECTED...WITH SOME UPPER 90S AND LOWER 100 DEGREE READINGS QUITE POSSIBLE ACROSS THE SOUTH. WITH DEWPOINTS GENERALLY IN THE 60S EACH DAY...AFTERNOON HEAT INDICES WILL LIKELY APPROACH 100 DEGREES EACH DAY...ESPECIALLY ACROSS THE SOUTH. EVEN IN THE SHORT TERM MODELS ARE HAVING A HARD TIME RESOLVING SHORTWAVES TRANSLATING THROUGH THE BROAD SOUTHWEST FLOW FROM THE WESTERN UPPER LOW INTO THE NORTHERN PLAINS AND SOUTHERN CANADA. THEREFORE A MODEL BLEND WAS UTILIZED FOR POPS THROUGH THE PERIOD. MODELS ARE TRYING TO DEVELOP CONVECTION ON SATURDAY AND SATURDAY NIGHT AS THERE WILL BE A SURFACE TROUGH TRACKING SLOWLY EAST ACROSS THE AREA THAT IS PROGGED TO BE OVER CENTRAL NORTH DAKOTA BY 00 UTC SUNDAY...WITH SHORTWAVE ENERGY MOVING INTO WESTERN NORTH DAKOTA. WE WILL HAVE ABUNDANT CAPE OVER THE AREA SATURDAY AFTERNOON BUT WILL LIKELY REMAIN CAPPED UNTIL SHORTWAVE ENERGY ARRIVES LATE IN THE DAY. THUS THE BEST THUNDERSTORM CHANCES ON SATURDAY ARE EXPECTED TO BE IN THE EVENING AND OVERNIGHT. SOME OF THESE COULD BE STRONG TO SEVERE. THEREAFTER...THUNDERSTORM CHANCES CANNOT BE RULED OUT EACH DAY AS THE LOWER ATMOSPHERE REMAINS MOIST AND UNSTABLE WITH SHORTWAVE ENERGY CONTINUING TO TRAVERSE THE AREA. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 937 AM CDT FRI AUG 23 2013 AT 9 AM CDT...WIDELY SCATTERED SHOWERS AND THUNDERSTORMS WERE ACROSS SOUTH CENTRAL NORTH DAKOTA IMPACTING KBIS. THUNDERSTORM HAZARD WILL BE TREATED WITH A VCTS (VICINITY) FORECAST FOR THUNDERSTORMS THROUGH 17Z. OTHERWISE...A WARM FRONT IN EASTERN MONTANA WILL MOVE SLOWLY EAST THIS AFTERNOON AND TONIGHT, THE WARM FRONT WILL BE THE FOCUS FOR SCATTERED TO WIDELY SCATTERED THUNDERSTORMS THIS AFTERNOON AND NIGHT AT KISN-KDIK-KBIS-KJMS. DUE TO UNCERTAINTY WILL KEEP THE VCTS FOR THIS SITES. VFR AT ALL TAF SITES. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...WAA SHORT TERM...KS LONG TERM...TWH AVIATION...WAA
AREA FORECAST DISCUSSION
NWS BISMARCK ND
643 AM CDT FRI AUG 23 2013 .UPDATE... ISSUED AT 643 AM CDT FRI AUG 23 2013 WEAK SHORTWAVE OVER SOUTHWEST NORTH DAKOTA IS PRODUCING ISOLATED SHOWERS AND A FEW RUMBLES OF THUNDER OVER CENTRAL NORTH DAKOTA. HAVE UPDATED POPS TO LATEST RADAR IMAGERY AND TRANSLATED THIS NORTH AND EAST THROUGH MID MORNING. ALSO KEPT ISOLATED THUNDER EXTENDING BACK INTO THE SOUTHWEST AS ANOTHER CELL HAD DEVELOPED OVER THE FAR SOUTHWEST. OTHERWISE NO CHANGES TO THE CURRENT FORECAST. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 250 AM CDT FRI AUG 23 2013 MAIN FORECAST CHALLENGE TODAY/TONIGHT WILL BE THUNDERSTORM POTENTIAL AND AREAL COVERAGE. LATEST WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL HIGH LOCATED OVER SOUTHWEST KANSAS WITH RIDGING NORTH INTO EASTERN MONTANA. LOW PRESSURE CIRCULATING OVER WESTERN OREGON IS EJECTING SEVERAL SHORTWAVES INTO AND OVER THE RIDGE . THE 00Z MODEL GUIDANCE AND HIGH RESOLUTION MODELS ALL OFFER DIFFERENT SCENARIOS FOR CONVECTION TODAY INTO FRIDAY NIGHT. HIGHEST CONFIDENCE IS IN THE NEAR TERM PERIOD WITH AN AREA OF SHOWERS AND THUNDERSTORMS IN SOUTHEAST MONTANA MARCHING TOWARD SOUTHWEST NORTH DAKOTA. THE LATEST HRRR HAS INITIALIZED WELL WITH THIS AREA AND WILL FOLLOW IT FOR THE MORNING HOURS. ESSENTIALLY THIS AREA IS FORECAST TO SLIDE ACROSS SOUTHWEST NORTH DAKOTA...THEN WEAKEN AND FALL APART AS IT APPROACHES SOUTH CENTRAL NORTH DAKOTA LATER THIS MORNING. THE SHORTWAVE CAUSING THIS PRECIPITATION IS SEEN OVER FAR SOUTHERN MONTANA NEAR AND ALONG THE WYOMING BORDER. IT IS FORECAST TO CONTINUE TO PUSH INTO SOUTHERN NORTH DAKOTA THIS AFTERNOON. VARIOUS CAPE/CIN SOUNDINGS PROFILES PER NAM/GFS ARGUES FOR A MODEL BLEND AT THIS TIME...AS IT IS UNCLEAR HOW MUCH OF A CAP REMAINS THIS AFTERNOON INTO FRIDAY NIGHT. IT SEEMS REASONABLE THAT WITH A LEE SIDE TROUGH IN EASTERN MONTANA TODAY...THIS WOULD BE THE AREA TO WATCH FOR THE MOST INTENSE THUNDERSTORMS TO DEVELOP THIS AFTERNOON...WITH CLOSE MONITORING THROUGH THE EVENING HOURS AS THEY MOVE NORTHEAST INTO WESTERN NORTH DAKOTA. CURRENT THINKING IS ANY CONVECTION IN CENTRAL NORTH DAKOTA THIS AFTERNOON SHOULD REMAIN ISOLATED IN NATURE. H85 TEMPS WILL BE RISING AGAIN IN THE WEST WITH STRONG WARM AIR ADVECTION RESULTING IN HIGHS IN THE LOW TO MID 90S. FOR FRIDAY NIGHT...IT APPEARS THE MAIN FOCUS AND THREAT FOR SHOWERS AND THUNDERSTORMS WILL RESIDE OVER NORTHERN NORTH DAKOTA. A SHORTWAVE IS FORECAST TO MOVE ACROSS NORTHEAST MONTANA BY 06Z SATURDAY...AND INTO SOUTHEASTERN SASKATCHEWAN BY 12Z SATURDAY. BEST FORCING IS IN THE NORTH AND HAVE HIGH CHANCE POPS FORECAST OVERNIGHT WITH SLIGHT CHANCE ELSEWHERE. OVERNIGHT LOWS WILL BE IN THE 60S. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 250 AM CDT FRI AUG 23 2013 MAIN FORECAST ISSUES IN THE LONG TERM WILL BE DAYTIME HIGH TEMPERATURES...POSSIBLE HEAT ADVISORY HIGHLIGHTS AND PERIODIC THUNDERSTORM CHANCES. THERE IS A CONTINUED AGREEMENT IN THE MEAN UPPER LEVEL FLOW WHICH FEATURES A STRONG RIDGE OVER THE CENTRAL U.S. THIS WILL RESULT IN TEMPERATURES WELL ABOVE NORMAL THROUGH THE EXTENDED PERIOD ACROSS WESTERN AND CENTRAL NORTH DAKOTA. DAYTIME HIGHS FROM THE UPPER 80S TO LOWER 90S NORTH AND LOWER TO MID 90S SOUTH ARE EXPECTED...WITH SOME UPPER 90S AND LOWER 100 DEGREE READINGS QUITE POSSIBLE ACROSS THE SOUTH. WITH DEWPOINTS GENERALLY IN THE 60S EACH DAY...AFTERNOON HEAT INDICES WILL LIKELY APPROACH 100 DEGREES EACH DAY...ESPECIALLY ACROSS THE SOUTH. EVEN IN THE SHORT TERM MODELS ARE HAVING A HARD TIME RESOLVING SHORTWAVES TRANSLATING THROUGH THE BROAD SOUTHWEST FLOW FROM THE WESTERN UPPER LOW INTO THE NORTHERN PLAINS AND SOUTHERN CANADA. THEREFORE A MODEL BLEND WAS UTILIZED FOR POPS THROUGH THE PERIOD. MODELS ARE TRYING TO DEVELOP CONVECTION ON SATURDAY AND SATURDAY NIGHT AS THERE WILL BE A SURFACE TROUGH TRACKING SLOWLY EAST ACROSS THE AREA THAT IS PROGGED TO BE OVER CENTRAL NORTH DAKOTA BY 00 UTC SUNDAY...WITH SHORTWAVE ENERGY MOVING INTO WESTERN NORTH DAKOTA. WE WILL HAVE ABUNDANT CAPE OVER THE AREA SATURDAY AFTERNOON BUT WILL LIKELY REMAIN CAPPED UNTIL SHORTWAVE ENERGY ARRIVES LATE IN THE DAY. THUS THE BEST THUNDERSTORM CHANCES ON SATURDAY ARE EXPECTED TO BE IN THE EVENING AND OVERNIGHT. SOME OF THESE COULD BE STRONG TO SEVERE. THEREAFTER...THUNDERSTORM CHANCES CANNOT BE RULED OUT EACH DAY AS THE LOWER ATMOSPHERE REMAINS MOIST AND UNSTABLE WITH SHORTWAVE ENERGY CONTINUING TO TRAVERSE THE AREA. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 643 AM CDT FRI AUG 23 2013 THE LATEST SATELLITE IMAGERY AND SURFACE OBSERVATIONS SHOW SCT/BKN LOW VFR CIGS AT KBIS/KJMS WITH MID/HIGH LEVEL CLOUDS ELSEWHERE. LOCAL RADAR WAS INDICATING A LINE OF VERY LIGHT SHOWERS APPROACHING KBIS AND THIS MIGHT MAKE IT INTO KJMS BY MID TO LATE MORNING...OTHERWISE EXPECT SCT/BKN VFR CIGS WITH A CHANCE FOR SHOWERS AND THUNDERSTORMS THROUGH THE TAF PERIOD. UNCERTAINTY CONTINUES IN REGARDS TO WHERE THE THUNDERSTORMS WILL INITIATE AND THEIR AREAL COVERAGE. THUS HAVE MAINTAINED A VCTS AT THOSE AERODROMES FROM THE PREVIOUS TAF ISSUANCE...AND WILL CONTINUE TO MONITOR FOR THUNDERSTORM DEVELOPMENT. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...TWH SHORT TERM...KS LONG TERM...TWH AVIATION...KS
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
1158 PM CDT SAT AUG 24 2013 .UPDATE... 06Z TAF DISCUSSION IN AVIATION SECTION. && .AVIATION... KCLL/KUTS/KCXO...SHOULD HAVE VFR CIGS TONIGHT WITH MAYBE AN HOUR OR SO OF 5SM AT KCXO IN THE MORNING BUT WILL NOT MENTION IN TAF. CONVECTION WILL BE MAIN ISSUE TOMORROW AS TROPICAL WAVE MOVES INLAND SLOWLY. MAY SEE A FEW SHOWERS A KCXO BUT THINK MAJORITY OF CONVECTION STAYS SOUTH OF THESE TERMINALS. OVERALL NOT MUCH CHANGE FROM THE 00Z TAF THINKING. KIAH/KHOU/KSGR...EXPECT VFR CIGS TONIGHT BUT INCREASING CLOUDS THROUGH THE MORNING. MAIN ISSUE WILL BE THE ONSET OF CONVECTION WITH TROPICAL WAVE MOVING INLAND. TROPICAL MOISTURE MAY BE SLOW TO MOVE INLAND SO THINK KIAH WILL BE ON EDGE OF CONVECTION. LOOKS LIKE THE 00Z MODEL RUNS ARE IN LINE WITH CURRENT TAF THINKING. DID TWEAK TIMING A BIT AND ADDED VCTS FOR KSGR/KHOU FOR EARLY AFTERNOON HOURS. ALSO INCREASED WIND FOR AFTERNOON AS PRESSURE GRADIENT TIGHTENS. KLBX/KGLS...MAIN ISSUE WILL BE SHRA DEVELOPING IN THE MORNING AND MOVING INLAND AS TROPICAL WAVE MOVES INLAND. WILL START VCSH AT 09Z FOR BOTH TERMINALS THEN DEVELOPING VCTS BY 15Z WITH MORE DAYTIME HEATING AND INCREASED TROPICAL MOISTURE. THINK THERE COULD BE A GOOD PERIOD OF SCT TSRA FOR BOTH TERMINALS FROM 15-21Z. FOR NOW WILL LEAVE VCTS GIVEN SCT NATURE OF CONVECTION. POSSIBLE TO TEMPO TSRA WITH APPROACHING CONVECTIVE CELLS. 39 && .PREV DISCUSSION... /ISSUED 1004 PM CDT SAT AUG 24 2013/ UPDATE... POPS AND WEATHER GRIDS FOR TONIGHT AND SUNDAY. DISCUSSION... EQUIPMENT ISSUE OF NOTE...THE GALVESTON TEMPERATURE IS TOO COOL. TECHNICIANS WILL CHECK OUT THE EQUIPMENT SOMETIME DURING THE NEXT 24 TO 48 HOURS. 00Z ANALYSIS AND MODEL FORECASTS PLACE THE EASTERLY WAVE OVER THE NORTHERN GULF ALONG THE LA COAST INTO THE CENTRAL GULF OF MEXICO. BOTH THE RAP AND NAM12 700 TO 300 MEAN LAYER FORECAST SHOWS THAT A SMALLER LOW PRESSURE TROUGH WILL APPROACH THE UPPER TEXAS COAST OVERNIGHT TONIGHT WITH THE MAIN WAVE THEN MOVING TO ALONG THE COAST DURING THE MID MORNING SUNDAY. BOTH MODELS KEEP THE BEST LAYER MOISTURE AND LIFT ALONG THE INTERSTATE 10 CORRIDOR SOUTH DURING THE MIDDAY AND AFTERNOON PERIOD. THE RIDGE TO THE NORTH MAY BE TOO MUCH FOR THE WAVE TO OVERCOME. EXPECT THE MAIN BULK OF THE RAIN CHANCES WILL OCCUR ALONG AND EAST OF THE WAVE AXIS...AND THERE MAY WELL BE A FAIRLY BIG DISCONTINUITY BETWEEN NO TO ISOLATED COVERAGE AND BE BULK OF THE ACTIVITY. FOR THAT REASON WILL ADJUST THE POPS DOWNWARD OVER THE INLAND AREAS TONIGHT AND FROM THE INTERSTATE 10 CORRIDOR NORTHWARD ON SUNDAY. ADJUSTED THE POPS SLIGHTLY DOWNWARD ELSEWHERE AS WELL BOTH PERIODS. 40 PREV DISCUSSION... /ISSUED 642 PM CDT SAT AUG 24 2013/ DISCUSSION... 00Z TAF DISCUSSION IN AVIATION SECTION. AVIATION... KCLL/KUTS/KCXO...OVER SHOULD HAVE VFR CIGS WITH MAYBE AN HOUR OR SO OF 5SM AT KCXO IN THE MORNING BUT WILL NOT MENTION IN TAF. CONVECTION WILL BE MAIN ISSUE TOMORROW AS TROPICAL WAVE MOVES INLAND SLOWLY. MAY SEE A FEW SHOWERS A KCXO BUT THINK MAJORITY OF CONVECTION STAYS SOUTH OF THESE TERMINALS. KIAH/KHOU/KSGR...EXPECT VFR CIGS TONIGHT BUT INCREASING CLOUDS THROUGH THE MORNING. MAIN ISSUE WILL BE THE ONSET OF CONVECTION WITH TROPICAL WAVE MOVING INLAND. TROPICAL MOISTURE MAY BE SLOW TO MOVE INLAND SO THINK KIAH WILL BE ON EDGE OF CONVECTION. WILL MENTION VCSH FOR ALL TAFS STARTING EARLIER IN THE DAY FOR KHOU/KSGR AND IN THE AFTERNOON FOR KIAH. WILL NEED TO EVALUATE VCTS FOR KHOU/KSGR FOR 17Z-20Z TIME FRAME FOR 06Z TAFS BASED ON 00Z MODEL RUNS. RIGHT NOW MORE CONFIDENT IN TS FOR KHOU/KSGR THAN KIAH. THINK 00Z MODEL RUNS WILL GIVE BETTER IDEA. ALSO INCREASED WIND FOR AFTERNOON AS PRESSURE GRADIENT TIGHTENS. KLBX/KGLS...MAIN ISSUE WILL BE SHRA DEVELOPING IN THE MORNING AND MOVING INLAND AS TROPICAL WAVE MOVES INLAND. WILL START VCSH AT 09Z FOR BOTH TERMINALS THEN DEVELOPING VCTS BY 15Z WITH MORE DAYTIME HEATING AND INCREASED TROPICAL MOISTURE. THINK THERE COULD BE A GOOD PERIOD OF SCT TSRA FOR BOTH TERMINALS FROM 15-21Z. WILL HOLD OFF ON TEMPO TSRA AND USE 00Z MODELS TO EVALUATE IF THERE WILL BE A TIME FRAME FOR MORE PRONOUNCED TSRA. 39 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 75 94 75 94 74 / 10 30 20 40 20 HOUSTON (IAH) 77 92 75 91 75 / 10 40 40 50 20 GALVESTON (GLS) 79 87 79 87 80 / 30 50 60 60 30 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ DISCUSSION...40
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
330 AM CDT SUN AUG 25 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 330 AM CDT SUN AUG 25 2013 MAIN FORECAST CONCERNS ARE ON TEMPERATURES TODAY AND THUNDERSTORM POTENTIAL TONIGHT. ...CURRENTLY AS OF 08Z... WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED TROUGHING ALONG THE WEST COAST OF NORTH AMERICA AND STRONG SUBTROPICAL RIDGING ENCOMPASSING KANSAS AND MISSOURI. AROUND THE RIDGING... MONSOONAL MOISTURE AND SHORTWAVES WERE EMANATING FROM BAJA CALIFORNIA / WHERE TROPICAL DEPRESSION IVO WAS LOCATED / NORTH- NORTHEAST INTO THE DAKOTAS. ONE SUCH MONSOONAL SHORTWAVE...ENHANCED BY CONVECTION...WAS TRACKING ACROSS NORTHERN ONTARIO. THE CONVECTION WITH THIS SHORTWAVE EXTENDS SOUTH INTO NORTHERN MN AND UPPER MI...BEING FED WITH MOISTURE BY A 35-50KT 850MB JET SEEN ON VWP AND PROFILER DATA EXTENDING FROM NEBRASKA INTO WESTERN LAKE SUPERIOR. EVEN A FEW STRAY SHOWERS EXTEND SOUTH INTO TREMPEALEAU COUNTY. REGARDING THE MOISTURE...GOES DERIVED PRECIPITABLE WATER IMAGERY SHOWED VALUES OF 1.5-2 INCHES ACROSS MUCH OF THE UPPER MIDWEST. THE CONVECTION IS ALSO RIDING ALONG THE EDGE OF A HOT AIRMASS ENCOMPASSING THE CENTRAL AND NORTHERN PLAINS AS WELL AS THE UPPER MIDWEST. RAP SHOWED 700MB TEMPS OF 12C OR HIGHER FROM DULUTH MN BACK INTO WESTERN NEBRASKA. MEANWHILE...DOWN AT 850MB...READINGS RANGED FROM 20-22C OVER THE FORECAST AREA TO 26-28C IN SOUTH DAKOTA. THE WARM AIRMASS EXTENDS DOWN TO THE SURFACE...WHERE OVER THE FORECAST AREA...A SOUTH BREEZE AND DEWPOINTS IN THE UPPER 60S TO LOW 70S HAS KEPT TEMPS AT OR ABOVE 70F. ALSO OF NOTE AT THE SURFACE IS A LOW PRESSURE TROUGH FROM INTERNATIONAL FALLS MN SOUTHWEST TO PHILLIP SOUTH DAKOTA. ...HAZARDS... 1. HEAT ADVISORY REMAINS ON TRACK FOR TODAY AND IN FACT HEAT INDICES MAY END UP HIGHER. 2. POTENTIAL CONVECTION TONIGHT COULD POSE A SEVERE RISK... PRIMARILY NORTH OF I-90. ISOLATED LARGE HAIL AND DAMAGING WINDS MAIN HAZARDS. ...SYNOPTIC OVERVIEW... 25.00Z MODELS ARE IN VERY GOOD AGREEMENT SHOWING THAT A WEAK 500MB RIDGE AXIS PRESENT ACROSS MN WILL FLATTEN OUT TODAY...THEN REBUILDS OVER THE DAKOTAS AHEAD OF A MORE DYNAMIC SHORTWAVE LIFTING OUT OF ARIZONA INTO WYOMING. WITHIN THE 500MB FLOW...MODELS SUGGEST A MONSOONAL SHORTWAVE SOMEWHERE IN NORTHWEST COLORADO OR EASTERN WYOMING CURRENTLY TO CROSS CENTRAL MN AND NORTHERN WI TONIGHT. ...DETAILS... THE FLATTENING OF THE 500MB FLOW TODAY WILL HELP TO SPREAD MORE OF THE WARMTH SEEN OVER SOUTH DAKOTA EASTWARD. 850MB TEMPS CLIMB TO 21-23C WHILE DOWN AT 925MB THEY JUMP TO 26-28C. MIXING TO THE 850MB TEMPS WHICH SEEMS QUITE REASONABLE GIVEN THAT WE SHOULD HAVE FULL SUN AND A BREEZY SOUTHWEST WIND YIELDS HIGHS IN THE LOW TO MID 90S. NOTICED THAT THE RAP IS EVEN WARMER...SUGGESTING HIGHS OF 95-100. THE REASON IS DUE TO SUPERADIABATIC EFFECTS...WHICH LOOK A BIT OVERDONE. WITH DEWPOINTS HOVERING IN THE UPPER 60S TO LOWER 70S ALL DAY...HEAT INDICES SHOULD TOP OUT BETWEEN 97-102. NOW THE BIGGER QUESTION IS CONVECTION CHANCES FOR LATE THIS AFTERNOON INTO TONIGHT. A COUPLE OF SCENARIOS EXIST... 1. THE 25.00Z NAM QUICKLY ERODES THE CAP BETWEEN 18-21Z FROM DULUTH INTO WESTERN UPPER MI...PERHAPS CAUSED BY AN OUTFLOW BOUNDARY EMANATING FROM CURRENT CONVECTION TRACKING ACROSS LAKE SUPERIOR. THIS CONVECTION THEN DIVES SOUTH INTO NORTHERN SECTIONS OF THE FORECAST AREA DURING THE EVENING INTO THE 850MB MOISTURE TRANSPORT AXIS...FOLLOWING CORFIDI VECTORS. THE CONVECTION EVENTUALLY WANES AFTER MIDNIGHT AS THE CAP RESTRENGTHENS. CONCERNED THAT THE NAM...IN PARTICULAR ITS BMJ CONVECTIVE SCHEME...MAY BE ERODING THE CAP TOO QUICKLY. 2. THE 25.00Z GFS...24.12Z ECMWF...THE BULK OF THE 25.03Z SREF MEMBERS AND 25.00Z HIRES-ARW GENERALLY WAIT TO BREAK OUT CONVECTION UNTIL AFTER 00Z ACROSS CENTRAL MN INTO NORTHERN WI...WHICH THEN DROPS SOUTH MORE INTO THE FORECAST AREA AFTER 06Z. AGAIN THE CONVECTION DIVES INTO THE 850MB MOISTURE TRANSPORT AXIS...FOLLOWING CORFIDI VECTORS. ADDITIONALLY...THESE MODELS SUGGEST THAT SHORTWAVE COMING OUT OF NORTHWEST COLORADO AND EASTERN WYOMING COULD BE AN ENHANCING PLAYER. 3. THE 24.12Z HIRES-ARW...25.00Z CANADIAN...UKMET AND ECMWF HAVE THE ONLY CONVECTION OCCURRING ACROSS NORTHERN WI AND UPPER MI TONIGHT... ON THE NOSE OF THE 850MB MOISTURE TRANSPORT. THEY SUGGESTS THE CAP HOLDS FOR LATE THIS AFTERNOON THROUGH TONIGHT...DIFFERENT FROM EITHER OF THE ABOVE 2 SCENARIOS. WHICH OF THE ABOVE 3 SCENARIOS PANS OUT BASICALLY DEPENDS ON THE STRENGTH OF THE CAP. FOR NOW LEANED TOWARDS SCENARIO NUMBER 2 AS IT HAS THE STRONGEST CONSENSUS...THOUGH CANNOT COMPLETELY RULE OUT NUMBER 3. THEREFORE...HAVE LIMITED PRECIPITATION CHANCES TO NO MORE THAN 50. THE SECOND SCENARIO ALSO POSES A MARGINAL SEVERE RISK NORTH OF I-90...GIVEN 0-6 KM SHEAR VALUES REACHING 25-30 KT AND STRONG INSTABILITY. MULTICELLS SEEM TO BE THE MOST LIKELY STORM MODE. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 330 AM CDT SUN AUG 25 2013 ...HAZARDS... 1. HEAT. HEAT ADVISORIES CONTINUE TO LOOK SOLID FOR MONDAY AND TUESDAY...AND THERE IS EVEN SOME CONCERN WE MAY HAVE TO UPGRADE PORTIONS OF THE AREA TO EXCESSIVE HEAT WARNING ON TUESDAY. THE ADVISORY MAY ALSO HAVE TO BE EXTENDED INTO WEDNESDAY SOUTH OF I-90. ANOTHER ROUND OF HEAT HAZARDS ARE POSSIBLE FOR LABOR DAY WEEKEND. 2. STORMS. POTENTIAL FOR SOME SEVERE WEATHER MONDAY NIGHT IF THE 25.00Z NAM/GFS ARE CORRECT WITH ANOTHER THUNDERSTORM COMPLEX MOVING THROUGH. ISOLATED LARGE HAIL AND DAMAGING WINDS MAIN HAZARDS. ...SYNOPTIC OVERVIEW... THE SUBTROPICAL HIGH CENTERED OVER KANSAS AND MISSOURI REMAINS PROGGED TO RETROGRADE WESTWARD TO SIT MOSTLY OVER KANSAS FOR TUESDAY THROUGH THURSDAY. THIS RETROGRESSION IS CAUSED BY DEEPER TROUGHING GRADUALLY FORMING OVER NEW ENGLAND. WHAT HAS BEEN PROBLEMATIC IS AFTER THURSDAY. 24.12Z ECMWF KEPT A NORTHWEST FLOW PATTERN GOING OVER THE FORECAST AREA FOR FRIDAY AND SATURDAY AS THE TROUGH PERSISTS IN NEW ENGLAND. HOWEVER...THE NEW 25.00Z ECMWF GOES ALONG WITH THE 25.00Z GFS TO ALLOW THE SUBTROPICAL HIGH AND ASSOCIATED RIDGING TO SHIFT EAST QUICKER. THIS MEANS THAT HEAT ISSUES ARE MORE LIKELY FOR LABOR DAY WEEKEND. ...PRECIPITATION DETAILS... ALL INDICATIONS ARE THAT SHOULD CONVECTION FROM TONIGHT SHOULD WEAKEN MONDAY MORNING DUE TO DIMINISHING MOISTURE TRANSPORT. MAINTAINED 20-40 PERCENT CHANCES MAINLY ACROSS WI FOR THE CONVECTION. THESE CHANCES SHIFT TO NORTH OF I-94 FOR THE AFTERNOON WHERE THE REMNANT OUTFLOW/WARM FRONTAL BOUNDARY MAY SERVE AS A TRIGGER FOR RENEWED CONVECTIVE DEVELOPMENT. OF COURSE...SHOULD THE UKMET/CANADIAN/ECMWF PAN OUT...MONDAY WILL BE DRY. 20-40 PERCENT CHANCES CONTINUE MONDAY NIGHT AND TUESDAY...GENERALLY ALONG AND NORTH OF I-94...WHERE ANOTHER THUNDERSTORM COMPLEX MAY SLIDE ACROSS AS INDICATED BY THE 25.00Z NAM/GFS. THESE STORMS WILL ALSO HAVE THAT STRONGER SHORTWAVE LIFTING OUT OF WYOMING AT 12Z MONDAY...HEADING INTO CENTRAL/NORTHERN MN BY 12Z TUESDAY FORCING IT. NOTE THAT THE 25.00Z ECMWF/CANADIAN/UKMET ARE FARTHER NORTH WITH THIS COMPLEX...SO MONDAY NIGHT AND TUESDAY COULD BE DRY AS WELL...THUS THE 20-40 PERCENT CHANCES. SIMILAR TO TONIGHT...SHOULD THE COMPLEX ROLL THROUGH...CANNOT RULE OUT SOME SEVERE WEATHER POTENTIAL WITH THEM. COLD FRONTAL PASSAGE OCCURS TUESDAY NIGHT BUT INDICATIONS ARE THAT THE AIRMASS MAY BE TOO CAPPED TO ALLOW ANY CONVECTION WITH IT. IN FACT MOST MODELS ARE DRY. THEREFORE REDUCED CHANCES SUCH THAT ONLY A 20 PERCENT CHANCE IS LEFT CLOSER TOWARDS CENTRAL WI TO BLEND WITH NEIGHBORING OFFICES. WEDNESDAY STILL LOOKS DRY WITH THE FRONT SOUTH OF THE AREA. SMALL CHANCES OF STORMS RETURN THURSDAY THROUGH FRIDAY AS THE FRONT COMES BACK AS A WARM FRONT. DRY CONDITIONS ARE ANTICIPATED SATURDAY WITH THE AREA IN THE WARM SECTOR. ...TEMPERATURE DETAILS... ON MONDAY...EVEN IF THERE ARE STORMS DISSIPATING IN THE MORNING AND NEW ONES FIRE LATER IN THE DAY...ALL INDICATIONS ARE THAT THERE WILL STILL BE PLENTY OF TIME FOR TEMPERATURES TO RECOVER. 925 AND 850MB TEMPS ARE ABOUT 1C HIGHER COMPARED TO TODAY...THUS ANTICIPATING HIGHS 1-2 F HIGHER. UPPER 60S/LOW 70S DEWPOINTS STILL SEEM REASONABLE RESULTING IN 100-105 HEAT INDICES. TUESDAY STILL LOOKS LIKE THE HOTTEST DAY AS 925-850MB WINDS VEER MORE WESTERLY...REALLY ADVECTING THE CORE OF THE HOT AIR OVER SOUTH DAKOTA AND NEBRASKA AT US. 925MB TEMPS CLIMB TO AROUND 30C OVER MOST OF THE FORECAST AREA WHICH IS USUALLY A GOOD CORRELATION FOR 100F TEMPS. RAISED HIGHS A LITTLE MORE AND FURTHER INCREASES MAY BE REQUIRED. DEWPOINTS LOOK LIKE THEY SHOULD HOLD THROUGH EVAPOTRANSPORATION IN THE UPPER 60S/LOW 70S...WHICH MEANS HEAT INDICES COULD CROSS THE 105 WARNING THRESHOLD IN SOME SPOTS. WEDNESDAY IS BECOMING A BIT MORE CONCERNING AS THE 25.00Z ECMWF/GFS ARE NOT AS QUICK BRINGING IN THE COOLER AIR BEHIND THE COLD FRONT. 925MB TEMPS STILL GET UP TO 28C OR HIGHER. THUS...INCREASED HIGHS A FEW DEGREES TO SHOW UPPER 80S TO LOW 90S. THESE MAY NEED TO BE INCREASED MORE...WHICH WOULD PROMPT AN EXTENSION OF THE HEAT ADVISORY ANOTHER DAY. THURSDAY AND FRIDAY WILL BE THE COOLEST DAYS...RELATIVELY SPEAKING AS 925MB TEMPS ONLY COOL TO 25-27C. THEN IF THE NEW 25.00Z ECMWF AND GFS ARE CORRECT...THESE CLIMB RIGHT BACK UP TO EVEN WARMER THAN THE CURRENT HEAT STRETCH...TO 30-32C FOR SATURDAY AND SUNDAY. IF THIS OCCURS...WE COULD EASILY BE LOOKING AT 100 DEGREE HEAT NEXT WEEKEND. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 1111 PM CDT SAT AUG 24 2013 BUFKIT SOUNDINGS CONTINUE TO POINT TO AN INCREASING LOW LEVEL JET THIS EVENING...WITH ABOUT 45 KTS BY 1500-2000 FT THROUGH 12-13Z OR SO. SEE CONFIRMATION OF THIS IN RECENT VAD/PROFILER WINDS. WILL CONTINUE THE MENTION OF LLWS IN THE TAFS AS A RESULT. TIGHT PRESSURE GRADIENT PERSISTS INTO SUNDAY NIGHT...WITH LATE MORNING/AFTERNOON MIXING RESULTING IN SOME HIGHER GUSTS. CONDITIONS WILL STAY VFR WITH ONLY A FEW HIGH CLOUDS. SUNDAY NIGHT...A SHORTWAVE TROUGH WILL TRACK EASTWARD ACROSS SOUTHERN CANADA...BUT LAY A WEST-EAST RUNNING SFC FRONT OVER THE REGION. INTERACTION WITH THE LOW LEVEL JET AND SOME INSTABILITY WILL RESULT IN SHRA/TS ALONG AND NORTH OF THE BOUNDARY...WHICH THE MODELS SUGGEST WILL SINK SOUTH OVERNIGHT...POTENTIALLY IMPACTING KRST/KLSE. THIS TREND HAS BEEN RATHER CONSISTENT IN THE NAM/GFS/ECMWF OVER THEIR PAST FEW RUNS...BUT NOT SURE HOW FAR SOUTH THIS PCPN WILL MAKE IT BEFORE A WEAKENING LOW LEVEL JET RESULTS IN A DECREASE IN AREAL COVERAGE. CLOUDS WILL BE ON THE INCREASE...BUT NORTH-SOUTH RUNNING X-SECTIONS AND SOUNDINGS KEEP ANY CIGS VFR. && .CLIMATE... ISSUED AT 330 AM CDT SUN AUG 25 2013 THE FOLLOWING ARE RECORD HIGHS FOR LA CROSSE AND ROCHESTER THROUGH LABOR DAY WEEKEND...GIVEN THE HEAT FORECAST. FOR MORE CLIMATE INFORMATION...SEE OUR WEBSITE AND THE TOP NEWS STORY ON THE HEAT. LA CROSSE ROCHESTER --------- --------- SUN 8/25 97/1948 97/1948 MON 8/26 96/1991 95/1955 TUE 8/27 95/1973 93/1984 WED 8/28 97/1955 96/1955 THU 8/29 95/1966 92/2012 FRI 8/30 97/2012 96/1941 SAT 8/31 95/1953 93/1960 SUN 9/1 98/1913 94/1937 MON 9/2 98/1937 94/1929 NORMAL HIGH TEMPERATURES THROUGH THIS PERIOD ARE 78-80 AT LA CROSSE AND 76-78 AT ROCHESTER. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...HEAT ADVISORY FROM NOON TODAY TO MIDNIGHT CDT TUESDAY NIGHT FOR WIZ017-029-032>034-041>044-053>055-061. MN...HEAT ADVISORY FROM NOON TODAY TO MIDNIGHT CDT TUESDAY NIGHT FOR MNZ079-086>088-094>096. IA...HEAT ADVISORY FROM NOON TODAY TO MIDNIGHT CDT TUESDAY NIGHT FOR IAZ008>011-018-019-029-030. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION...RIECK CLIMATE...AJ
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
1105 AM EDT SUN AUG 25 2013 .LATE MORNING UPDATE... OVERALL CLOUD COVER IS A BIT MORE ROBUST THAN ORIGINALLY EXPECTED THANKS IN PART TO CONVECTIVE BLOW-OFF FROM ALL THE STORMS OFFSHORE THIS MORNING. HAVE LOWERED HIGH TEMPS A COUPLE OF DEGREES TO ACCOUNT FOR THE PARTIAL LOSS OF INSOLATION DURING THESE PEAK HEATING HOURS. THE WEAKER HEATING MAY ALSO HAVE A NEGATIVE IMPACT ON THE STRENGTH OF THE SEA-BREEZE. UPPER 80S WATER TEMPS AND UPPER 80S TEMPS DON`T LEAD TO MUCH OF A DISCONTINUITY. WILL HAVE TO SEE JUST HOW ANY LOSS OF SEA-BREEZE STRENGTH WILL IMPACT THE AFTERNOON CONVECTION. SURE THERE ARE STILL PLENTY OF RESIDUAL BOUNDARIES OUT THERE FROM ALL THE ACTIVITY THE PAST FEW DAYS TO GET SOME ACTIVITY GOING...BUT THE LOSS OR WEAKNESS OF THIS MAIN MECHANISM WOULD LIKELY HAVE A NEGATIVE IMPACT ON THE FOCUS FOR RISING MOTION. AT THE VERY LEAST WOULD EXPECT A TEMPORAL DELAY IN GOOD CONVECTIVE COVERAGE COMPARED TO PREVIOUS DAYS. && .MID MORNING UPDATE (REST OF TODAY THROUGH MONDAY)... 13Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS MUCH OF THE CENTRAL AND EASTERN PORTIONS OF THE CONUS UNDER THE DOMAIN OF A LARGE AND AMPLIFIED UPPER LEVEL RIDGE. THIS RIDGE CENTER/AXIS EXIST NEAR AND JUST TO THE WEST OF THE MIDDLE MS VALLEY. FURTHER DOWNSTREAM... LONGWAVE TROUGHING HAS EXITED THE EASTERN SEABOARD WITH A WEAK EXTENSION OF THE TROUGH AXIS BACK TO THE SOUTHWEST TOWARD THE FLORIDA PENINSULA. WV IMAGERY STILL SHOWS PLENTY OF MID/HIGH LEVEL MOISTURE IN PLACE OVER THE PENINSULA TODAY...BUT AN AREA OF MUCH DRIER AIR ALOFT AND DECENT SYNOPTIC SUPPRESSION CAN BE SEEN OVER THE CAROLINAS/GEORGIA. THIS SYNOPTIC SETUP WILL MAKE A PUSH INTO NORTHERN FLORIDA LATER TODAY...BUT GLOBAL GUIDANCE AGREES ON A MORE SIGNIFICANT PUSH SOUTHWARD DOWN THE PENINSULA OCCURRING TONIGHT AND MONDAY MORNING. THIS ACTION WILL SCOUR OUT THE DEEPER MOISTURE AND ALONG WITH INCREASING ANTI-CYCLONIC FLOW ALOFT/DEEP LAYER SUPPRESSION WILL HELP TO BRING OUR RAIN CHANCES BACK DOWN TO CLIMO NORMS...OR LESS...FOR THE EARLY PORTION OF THE UPCOMING WORK WEEK. AT THE SURFACE...STRONG RIDGE OF HIGH PRESSURE IS CENTERED OVER THE MID-ATLANTIC/CAROLINAS AND WILL PROVIDE A NE TO EAST LOW LEVEL FLOW THROUGH THE PERIOD AS IT SLOWLY SINKS SOUTH AND BEGINS TO WEAKEN. REST OF TODAY...WELL DEFINED LAND BREEZE AIDED BY THE SYNOPTIC E/NE FLOW IS RESULTING IN PLENTY OF LOW LEVEL CONVERGENCE OFFSHORE THIS MORNING. THIS CONVERGENCE ALONG WITH THE DEEP MOISTURE AND WEAK SYNOPTIC SUPPORT FOR LIFT OVERHEAD IS MAKING FOR AN ACTIVE MORNING IN TERMS OF THUNDERSTORMS AWAY FROM THE COAST. MARINERS STAYING CLOSE TO THE COAST THIS MORNING SHOULD BE OK...BUT ANYONE PLANNING TO GO FURTHER OFFSHORE BEYOND 15-20 MILES SHOULD EXPECT THE OCCASIONAL ROUGHER WEATHER. THIS ACTIVITY WILL WEAKEN/DIMINISH SOMEWHAT INTO THE AFTERNOON AS THE LAND-BREEZE COLLAPSES. HOWEVER...DUE TO THE FAVORABLE ENVIRONMENT ALOFT...PROB WILL NOT COMPLETELY DISAPPEAR AS OFTEN HAPPENS IN THE SUMMER. BIT OF A DIFFICULT FORECAST PATTERN FOR THE LAND ZONES...ESPECIALLY FOR THOSE AREA NORTH OF TAMPA BAY. LESS FAVORABLE ATMOSPHERIC CONDITIONS TO SUPPORT NUMEROUS STORMS WILL BE SLIDING SOUTH TOWARD THE AREA DURING THE DAY...BUT IT IS BE A CLOSE CALL WHETHER IT ARRIVES IN TIME THIS AFTERNOON TO REALLY MAKE AN IMPACT FOR PLACES LIKE LEVY/CITRUS/SUMTER/HERNANDO. THERE CERTAINLY WILL BE A DECREASE IN DEEP MOISTURE FOR THESE AREA BY LATE IN THE DAY...HOWEVER THESE MOISTURE/PW GRADIENTS CAN ALSO BE THE FOCUS FOR CONVECTIVE ACTIVITY. WITH THIS IN MIND...WILL NOT GET TOO DETAILED WITH THE FORECAST AND KEEP CHANCE POP WORDING NORTH OF TAMPA BAY...AND LIKELY POP WORDING FURTHER SOUTH WITHIN THE ZONE OF DEEPEST MOISTURE AND UPPER LEVEL TROUGH SUPPORT. MID-LEVEL LAPSE RATES ARE NOTHING IMPRESSIVE TODAY WHICH SHOULD KEEP THE CHANCES FOR SEVERE STORMS GENERALLY DOWN. HOWEVER...ONCE AGAIN THE CONCERN WILL BE THE POTENTIAL FOR LOCALLY HEAVY RAINS OVER SATURATED SOILS DUE TO WEAK WIND FIELDS AND RESULTING SLOW STORM MOTION. WE DO HAVE SOME STRONGER FLOW TOWARD THE TOP OF THE TROP TODAY...BUT ONLY THE TALLEST OF STORMS WILL REALLY BE ABLE TO FEEL THIS IMPACT...WITH THE MAJORITY OF THE STORMS MASS COLUMN DEVELOPING WITHIN A WEAK FLOW PATTERN. EVENING STORMS WILL SHIFT/RE-DEVELOP OFFSHORE AFTER MIDNIGHT LEAVING THE LAND ZONES GENERALLY DRY AFTER 02-03Z. THE LESS FAVORABLE CONDITIONS (FOR DEEP CONVECTION) PUSHING SOUTH MAY KEEP THE BEST OFFSHORE STORM COVERAGE TO THE SOUTH OF TAMPA BAY LATE TONIGHT INTO MONDAY MORNING COMPARED TO TODAY...AND THIS SEEMS TO BE A THEME IN MANY OF THE LARGER SCALE PARAMETRIZED GUIDANCE. MONDAY... DEEPER MOISTURE IS SHOWN TO EXIT SOUTH OF LEE/CHARLOTTE COUNTIES BY EARLY AFTERNOON ALONG WITH THE LINGERING SYNOPTIC SUPPORT FROM THE UPPER TROUGH. GFS IS ACTUALLY SHOWING SOME RATHER IMPRESSIVE Q-VECTOR DIVERGENCE OVERHEAD FOR MUCH OF THE REGION TOMORROW WHICH WILL WORK AGAINST ANOTHER ABNORMALLY WET AFTERNOON/EVENING. WILL BE CURIOUS TO SEE WHAT KIND OF POPS COME OUT WITH THE 12Z PACKAGE...BUT CAN NOT SEE GOING ANY HIGHER THAN WHAT IS CURRENTLY IN THE GRIDS. GIVEN THE FORECAST ATMOSPHERIC COLUMN...A MORE CLIMO CHANCE POP (40-50%) TYPE STORM COVERAGE CAN BE EXPECTED SOUTH OF I-4...AND BELOW CLIMO (20-30%) POP COVERAGE FURTHER NORTH THROUGH THE NATURE COAST. ENJOY YOUR SUNDAY! && .AVIATION... LOW CIGS AND PATCHY BR AVOIDED THE TAF TERMINALS THIS MORNING. OTHERWISE EXPECT VFR UNTIL THIS AFTERNOON WHEN VCNTY SHRA/TSRA FORM DURING A 19Z-02Z WINDOW...WITH SOME TEMPO MVFR/LCL IFR PSBL. HIGH PRESSURE BUILDING IN TO THE NORTH WILL PROVIDE A NE FLOW THAT KEEPS THE AFTERNOON SEA BREEZE CLOSE TO THE COAST. && .MARINE... A STRONG RIDGE OF HIGH PRESSURE WELL TO OUR NORTH ALONG THE MID-ATLANTIC STATES WILL PROVIDE AN EASTERLY WIND FLOW THROUGH THE EARLY NEXT WEEK. THE GRADIENT IS EXPECTED TO RELAX ENOUGH THIS AFTERNOON TO PROVIDE FOR AN ONSHORE SEA BREEZE TO DEVELOP. THE RIDGE TO OUR NORTH WILL TAKE A POSITION BY TONIGHT AND MONDAY NIGHT TO PROVIDE ENHANCED EASTERLY FLOW EACH NIGHT INTO THE EARLY MORNING HOURS. WINDS MAY AT TIMES APPROACH CAUTIONARY LEVELS...ESPECIALLY TO THE NORTH OF TARPON SPRINGS. && .FIRE WEATHER... NO CONCERNS OVERALL. SOME PATCHY GROUND FOG IS POSSIBLE AROUND SUNRISE EACH DAY IN NORMALLY FOG-PRONE AREAS AND THOSE THAT RECEIVE RAINFALL. && .PRELIMINARY POINT TEMPS/POPS... TPA 89 75 90 75 / 60 40 30 30 FMY 89 73 88 72 / 60 40 60 20 GIF 90 72 90 72 / 60 30 40 30 SRQ 88 74 89 73 / 60 40 40 30 BKV 89 71 91 69 / 50 40 20 20 SPG 88 76 89 77 / 60 40 30 30 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...NONE. GULF WATERS...NONE. && $$ UPDATE/MARINE...MROCZKA AVIATION...RUDE
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
915 AM EDT SUN AUG 25 2013 .UPDATE (REST OF TODAY THROUGH MONDAY)... 13Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS MUCH OF THE CENTRAL AND EASTERN PORTIONS OF THE CONUS UNDER THE DOMAIN OF A LARGE AND AMPLIFIED UPPER LEVEL RIDGE. THIS RIDGE CENTER/AXIS EXIST NEAR AND JUST TO THE WEST OF THE MIDDLE MS VALLEY. FURTHER DOWNSTREAM... LONGWAVE TROUGHING HAS EXITED THE EASTERN SEABOARD WITH A WEAK EXTENSION OF THE TROUGH AXIS BACK TO THE SOUTHWEST TOWARD THE FLORIDA PENINSULA. WV IMAGERY STILL SHOWS PLENTY OF MID/HIGH LEVEL MOISTURE IN PLACE OVER THE PENINSULA TODAY...BUT AN AREA OF MUCH DRIER AIR ALOFT AND DECENT SYNOPTIC SUPPRESSION CAN BE SEEN OVER THE CAROLINAS/GEORGIA. THIS SYNOPTIC SETUP WILL MAKE A PUSH INTO NORTHERN FLORIDA LATER TODAY...BUT GLOBAL GUIDANCE AGREES ON A MORE SIGNIFICANT PUSH SOUTHWARD DOWN THE PENINSULA OCCURRING TONIGHT AND MONDAY MORNING. THIS ACTION WILL SCOUR OUT THE DEEPER MOISTURE AND ALONG WITH INCREASING ANTI-CYCLONIC FLOW ALOFT/DEEP LAYER SUPPRESSION WILL HELP TO BRING OUR RAIN CHANCES BACK DOWN TO CLIMO NORMS...OR LESS...FOR THE EARLY PORTION OF THE UPCOMING WORK WEEK. AT THE SURFACE...STRONG RIDGE OF HIGH PRESSURE IS CENTERED OVER THE MID-ATLANTIC/CAROLINAS AND WILL PROVIDE A NE TO EAST LOW LEVEL FLOW THROUGH THE PERIOD AS IT SLOWLY SINKS SOUTH AND BEGINS TO WEAKEN. REST OF TODAY...WELL DEFINED LAND BREEZE AIDED BY THE SYNOPTIC E/NE FLOW IS RESULTING IN PLENTY OF LOW LEVEL CONVERGENCE OFFSHORE THIS MORNING. THIS CONVERGENCE ALONG WITH THE DEEP MOISTURE AND WEAK SYNOPTIC SUPPORT FOR LIFT OVERHEAD IS MAKING FOR AN ACTIVE MORNING IN TERMS OF THUNDERSTORMS AWAY FROM THE COAST. MARINERS STAYING CLOSE TO THE COAST THIS MORNING SHOULD BE OK...BUT ANYONE PLANNING TO GO FURTHER OFFSHORE BEYOND 15-20 MILES SHOULD EXPECT THE OCCASIONAL ROUGHER WEATHER. THIS ACTIVITY WILL WEAKEN/DIMINISH SOMEWHAT INTO THE AFTERNOON AS THE LAND-BREEZE COLLAPSES. HOWEVER...DUE TO THE FAVORABLE ENVIRONMENT ALOFT...PROB WILL NOT COMPLETELY DISAPPEAR AS OFTEN HAPPENS IN THE SUMMER. BIT OF A DIFFICULT FORECAST PATTERN FOR THE LAND ZONES...ESPECIALLY FOR THOSE AREA NORTH OF TAMPA BAY. LESS FAVORABLE ATMOSPHERIC CONDITIONS TO SUPPORT NUMEROUS STORMS WILL BE SLIDING SOUTH TOWARD THE AREA DURING THE DAY...BUT IT IS BE A CLOSE CALL WHETHER IT ARRIVES IN TIME THIS AFTERNOON TO REALLY MAKE AN IMPACT FOR PLACES LIKE LEVY/CITRUS/SUMTER/HERNANDO. THERE CERTAINLY WILL BE A DECREASE IN DEEP MOISTURE FOR THESE AREA BY LATE IN THE DAY...HOWEVER THESE MOISTURE/PW GRADIENTS CAN ALSO BE THE FOCUS FOR CONVECTIVE ACTIVITY. WITH THIS IN MIND...WILL NOT GET TOO DETAILED WITH THE FORECAST AND KEEP CHANCE POP WORDING NORTH OF TAMPA BAY...AND LIKELY POP WORDING FURTHER SOUTH WITHIN THE ZONE OF DEEPEST MOISTURE AND UPPER LEVEL TROUGH SUPPORT. MID-LEVEL LAPSE RATES ARE NOTHING IMPRESSIVE TODAY WHICH SHOULD KEEP THE CHANCES FOR SEVERE STORMS GENERALLY DOWN. HOWEVER...ONCE AGAIN THE CONCERN WILL BE THE POTENTIAL FOR LOCALLY HEAVY RAINS OVER SATURATED SOILS DUE TO WEAK WIND FIELDS AND RESULTING SLOW STORM MOTION. WE DO HAVE SOME STRONGER FLOW TOWARD THE TOP OF THE TROP TODAY...BUT ONLY THE TALLEST OF STORMS WILL REALLY BE ABLE TO FEEL THIS IMPACT...WITH THE MAJORITY OF THE STORMS MASS COLUMN DEVELOPING WITHIN A WEAK FLOW PATTERN. EVENING STORMS WILL SHIFT/RE-DEVELOP OFFSHORE AFTER MIDNIGHT LEAVING THE LAND ZONES GENERALLY DRY AFTER 02-03Z. THE LESS FAVORABLE CONDITIONS (FOR DEEP CONVECTION) PUSHING SOUTH MAY KEEP THE BEST OFFSHORE STORM COVERAGE TO THE SOUTH OF TAMPA BAY LATE TONIGHT INTO MONDAY MORNING COMPARED TO TODAY...AND THIS SEEMS TO BE A THEME IN MANY OF THE LARGER SCALE PARAMETRIZED GUIDANCE. MONDAY... DEEPER MOISTURE IS SHOWN TO EXIT SOUTH OF LEE/CHARLOTTE COUNTIES BY EARLY AFTERNOON ALONG WITH THE LINGERING SYNOPTIC SUPPORT FROM THE UPPER TROUGH. GFS IS ACTUALLY SHOWING SOME RATHER IMPRESSIVE Q-VECTOR DIVERGENCE OVERHEAD FOR MUCH OF THE REGION TOMORROW WHICH WILL WORK AGAINST ANOTHER ABNORMALLY WET AFTERNOON/EVENING. WILL BE CURIOUS TO SEE WHAT KIND OF POPS COME OUT WITH THE 12Z PACKAGE...BUT CAN NOT SEE GOING ANY HIGHER THAN WHAT IS CURRENTLY IN THE GRIDS. GIVEN THE FORECAST ATMOSPHERIC COLUMN...A MORE CLIMO CHANCE POP (40-50%) TYPE STORM COVERAGE CAN BE EXPECTED SOUTH OF I-4...AND BELOW CLIMO (20-30%) POP COVERAGE FURTHER NORTH THROUGH THE NATURE COAST. ENJOY YOUR SUNDAY! && .AVIATION... LOW CIGS AND PATCHY BR AVOIDED THE TAF TERMINALS THIS MORNING. OTHERWISE EXPECT VFR UNTIL THIS AFTERNOON WHEN VCNTY SHRA/TSRA FORM DURING A 19Z-02Z WINDOW...WITH SOME TEMPO MVFR/LCL IFR PSBL. HIGH PRESSURE BUILDING IN TO THE NORTH WILL PROVIDE A NE FLOW THAT KEEPS THE AFTERNOON SEA BREEZE CLOSE TO THE COAST. && .MARINE... A STRONG RIDGE OF HIGH PRESSURE WELL TO OUR NORTH ALONG THE MID-ATLANTIC STATES WILL PROVIDE AN EASTERLY WIND FLOW THROUGH THE EARLY NEXT WEEK. THE GRADIENT IS EXPECTED TO RELAX ENOUGH THIS AFTERNOON TO PROVIDE FOR AN ONSHORE SEA BREEZE TO DEVELOP. THE RIDGE TO OUR NORTH WILL TAKE A POSITION BY TONIGHT AND MONDAY NIGHT TO PROVIDE ENHANCED EASTERLY FLOW EACH NIGHT INTO THE EARLY MORNING HOURS. WINDS MAY AT TIMES APPROACH CAUTIONARY LEVELS...ESPECIALLY TO THE NORTH OF TARPON SPRINGS. && .FIRE WEATHER... NO CONCERNS OVERALL. SOME PATCHY GROUND FOG IS POSSIBLE AROUND SUNRISE EACH DAY IN NORMALLY FOG-PRONE AREAS AND THOSE THAT RECEIVE RAINFALL. && .PRELIMINARY POINT TEMPS/POPS... TPA 89 75 90 75 / 60 40 30 30 FMY 89 73 88 72 / 60 40 60 20 GIF 90 72 90 72 / 60 30 40 30 SRQ 88 74 89 73 / 60 40 40 30 BKV 89 71 91 69 / 50 40 20 20 SPG 88 76 89 77 / 60 40 30 30 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...NONE. GULF WATERS...NONE. && $$ UPDATE/MARINE...MROCZKA AVIATION...RUDE
AREA FORECAST DISCUSSION
NWS GOODLAND KS
920 AM MDT SUN AUG 25 2013 .UPDATE... ISSUED AT 912 AM MDT SUN AUG 25 2013 DECREASED WINDS A FEW KNOTS FOR THIS AFTERNOON BASED ON WINDS MIXING DOWN FROM 700MB WHERE THE TOP OF THE MIXED LAYER WILL BE. SO FAR THE DAY LOOKS VERY SIMILAR TO YESTERDAY. AM A BIT CONCERNED WITH THE MORE SOUTH-SOUTHWEST DIRECTION OF THE WINDS AS THIS MAY ALLOW DEW POINTS TO FALL A FEW MORE DEGREES THAN YESTERDAY. SO FAR LOOKS LIKE WINDS/RELATIVE HUMIDITIES WILL BE VERY CLOSE TO MEETING CRITICAL FIRE WEATHER CONDITIONS. AT THIS TIME...AND BASED ON WHAT HAPPENED YESTERDAY...DO NOT HAVE ENOUGH CONFIDENCE TO ISSUE ANY FIRE WEATHER PRODUCTS FOR THE AFTERNOON. THE RECENT RAINS ALSO ADD MORE COMPLEXITY TO WHERE THE FUELS WILL BE FAVORABLE FOR RAPID FIRE GROWTH AND WHERE THEY WONT BE. AT THIS POINT CHEYENNE TO RAWLINS AND SHERMAN TO THOMAS COUNTIES AND RED WILLOW COUNTY LOOK TO BE THE MOST FAVORABLE FOR CRITICAL FIRE WEATHER CONDITIONS. WILL CONTINUE TO MONITOR IN CASE A FIRE WEATHER PRODUCT IS NEEDED. && .SHORT TERM...(TODAY THROUGH TUESDAY NIGHT) ISSUED AT 254 AM MDT SUN AUG 25 2013 LITTLE IS GOING TO CHANGE REGARDING THE THE LARGE SCALE PATTERN ACROSS THE CENTRAL US...WITH HOT/DRY CONDITIONS EXPECTED OVER OUR CWA. LARGE H5 RIDGE REMAIN IN PLACE OVER THE CENTRAL CONUS...WITH LATEST RAP ANALYSIS SHOWS 595DM CENTER ACROSS KS/MO STATE LINE. GFS/NAM SHOW HEIGHTS CONTINUING TO RISE THROUGH THE DAY WITH 597-598DM CENTER BY 00Z THIS AFTERNOON. WITH DRY/STABLE AIR MASS IN PLACE PRIMARY CONCERN WILL CONTINUE TO BE HOT TEMPERATURES AND MARGINAL FIRE WEATHER CONDITIONS IN THE WEST. STRONG LEE TROUGH WILL REMAIN IN PLACE THROUGH MONDAY...WITH STRONG SOUTHERLY PRESSURE GRADIENT OVER OUR CWA. BREEZY TO WINDY CONDITIONS ARE EXPECTED TODAY THROUGH MONDAY...WITH LATEST GUIDANCE BEGINNING TO SHOW WINDY CONDITIONS FURTHER WEST WHERE LOWER RH VALUES WILL BE. AT THIS POINT...IT APPEARS WE WILL BE JUST OUTSIDE OF RFW CRITERIA FOR RH...THOUGH I COULDNT RULE OUT A FEW WESTERN LOCATIONS FALLING JUST WITHIN LOCAL CRITERIA. I AM NOT PLANNING ON ISSUING A WARNING AT THIS TIME DUE TO THE MARGINAL AND ISOLATED NATURE OF THESE CONDITIONS. THERE IS ALSO A QUESTION REGARDING FUELS...WITH ISOLATED PARTS OF OUR CWA HAVING RECEIVED QUITE A BIT OF RAINFALL SINCE LATE JUNE DESPITE THE MAJORITY OF THE AREA REMAINING IN DROUGHT. SATELLITE DERIVED GREENNESS PRODUCTS SHOW PREDOMINANTLY GREEN FUELS OVER PARTS OF THE TRI-STATE AREA...THOUGH THERE ARE PARTS OF MANY COUNTIES THAT FALL BELOW NORMAL GREENNESS LEVELS. IF CONDITIONS WERE LESS MARGINAL...THE STATUS OF FUELS MIGHT STILL PREEMPT ISSUANCE OF RFW FOR PARTS OF OUR CWA. REGARDING HIGH/LOW TEMPS...I USED BIASES FROM SUN AS THE BASIS FOR THE FORECAST THROUGH TUE WITH VERY SIMILAR AIR MASS IN PLACE EACH DAY. I ALSO TRENDED LOW TEMPS UP FROM PREVIOUS FORECAST WITH BREEZY WINDS LIKELY IMPACTING RADIATIONAL COOLING EACH NIGHT. FORECAST IS STILL CALLING FOR UPPER 90S/LOW 100S EACH AFTERNOON..AND BY MON/TUE I WOULDNT BE SURPRISED IF WE SAW A FEW LOCATIONS COME WITHIN A FEW DEGREES OF RECORD HIGHS. .LONG TERM...(WEDNESDAY THROUGH SATURDAY) ISSUED AT 254 AM MDT SUN AUG 25 2013 MUCH OF THE SAME FOR THE SECOND HALF OF THIS WEEK WITH HOT AND DRY CONDITIONS CONTINUING. A BROAD H5 RIDGE CENTERED OVER KANSAS WILL BE WELL-ESTABLISHED BY MID-WEEK. THIS RIDGE WILL GRADUALLY BUILD WEST OVER THE REST OF THE WEEK...KEEPING THE SENSIBLE WX FAIRLY BENIGN. THE ONLY INTERESTING FEATURE IS A WEAK VORT MAX THAT MAY MOVE ACROSS EASTERN COLORADO INTO WESTERN KANSAS LATE THURSDAY. WHILE THERE WILL BE SOME UPPER-LEVEL MOISTURE...SOUNDINGS APPEAR TOO STABLE TO SUPPORT WIDESPREAD STORMS. THE OPERATIONAL GFS PRINTS OUT SOME QPF IN WESTERN KANSAS FROM THIS...AS WELL AS JUST ONE OF THE TWELVE ENSEMBLE PERTURBATIONS...SO HAVE LITTLE CONFIDENCE IN ANY PRECIP BEING REALIZED. RIDGE CONTINUES DRIFTING WESTWARD OVER THE WEEKEND WHILE AN UPPER LOW MOVING INTO THE PACIFIC NORTHWEST MAY HELP TO WEAKEN THE RIDGE LATE IN THE WEEKEND. FOR NOW...NO PRECIP CHANCES THROUGH SATURDAY AFTERNOON. FOR TEMPS...ALL GUIDANCE CONTINUES TO TREND WARMER FOR THE PERIOD WITH 850MB TEMPS IN THE LOW 30S C. TEMPS WILL BE NEARLY THE SAME EVERY DAY...HIGHS IN THE MID TO UPPER 90S AND LOWS IN THE MID 60S TO LOW 70S. HIGHS ARE NOT EXPECTED TO BE RECORD BREAKING...BUT A FEW STATIONS COULD APPROACH RECORD HIGHS ANY DAY OF THE EXTENDED. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING) ISSUED AT 529 AM MDT SUN AUG 25 2013 VFR CONDITIONS WILL CONTINUE THROUGH THE TAF PERIOD AT BOTH KGLD AND KMCK...WITH ONLY PASSING HIGH CLOUDS. BREEZY CONDITIONS WILL REDEVELOP THIS MORNING AND CONTINUE THROUGH AT LEAST THE EARLY EVENING HOURS...POSSIBLY INTO THE OVERNIGHT AS TIGHT PRESSURE GRADIENT REMAINS IN PLACE. STRONGEST WIND GUSTS WILL BE THIS AFTERNOON WHEN GUSTS 30-35KT WILL BE POSSIBLE AT BOTH TERMINALS. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...JTL SHORT TERM...DR LONG TERM...JJM AVIATION...DR
AREA FORECAST DISCUSSION
NWS GOODLAND KS
531 AM MDT SUN AUG 25 2013 .SHORT TERM...(TODAY THROUGH TUESDAY NIGHT) ISSUED AT 254 AM MDT SUN AUG 25 2013 LITTLE IS GOING TO CHANGE REGARDING THE THE LARGE SCALE PATTERN ACROSS THE CENTRAL US...WITH HOT/DRY CONDITIONS EXPECTED OVER OUR CWA. LARGE H5 RIDGE REMAIN IN PLACE OVER THE CENTRAL CONUS...WITH LATEST RAP ANALYSIS SHOWS 595DM CENTER ACROSS KS/MO STATE LINE. GFS/NAM SHOW HEIGHTS CONTINUING TO RISE THROUGH THE DAY WITH 597-598DM CENTER BY 00Z THIS AFTERNOON. WITH DRY/STABLE AIR MASS IN PLACE PRIMARY CONCERN WILL CONTINUE TO BE HOT TEMPERATURES AND MARGINAL FIRE WEATHER CONDITIONS IN THE WEST. STRONG LEE TROUGH WILL REMAIN IN PLACE THROUGH MONDAY...WITH STRONG SOUTHERLY PRESSURE GRADIENT OVER OUR CWA. BREEZY TO WINDY CONDITIONS ARE EXPECTED TODAY THROUGH MONDAY...WITH LATEST GUIDANCE BEGINNING TO SHOW WINDY CONDITIONS FURTHER WEST WHERE LOWER RH VALUES WILL BE. AT THIS POINT...IT APPEARS WE WILL BE JUST OUTSIDE OF RFW CRITERIA FOR RH...THOUGH I COULDNT RULE OUT A FEW WESTERN LOCATIONS FALLING JUST WITHIN LOCAL CRITERIA. I AM NOT PLANNING ON ISSUING A WARNING AT THIS TIME DUE TO THE MARGINAL AND ISOLATED NATURE OF THESE CONDITIONS. THERE IS ALSO A QUESTION REGARDING FUELS...WITH ISOLATED PARTS OF OUR CWA HAVING RECEIVED QUITE A BIT OF RAINFALL SINCE LATE JUNE DESPITE THE MAJORITY OF THE AREA REMAINING IN DROUGHT. SATELLITE DERIVED GREENNESS PRODUCTS SHOW PREDOMINANTLY GREEN FUELS OVER PARTS OF THE TRI-STATE AREA...THOUGH THERE ARE PARTS OF MANY COUNTIES THAT FALL BELOW NORMAL GREENNESS LEVELS. IF CONDITIONS WERE LESS MARGINAL...THE STATUS OF FUELS MIGHT STILL PREEMPT ISSUANCE OF RFW FOR PARTS OF OUR CWA. REGARDING HIGH/LOW TEMPS...I USED BIASES FROM SUN AS THE BASIS FOR THE FORECAST THROUGH TUE WITH VERY SIMILAR AIR MASS IN PLACE EACH DAY. I ALSO TRENDED LOW TEMPS UP FROM PREVIOUS FORECAST WITH BREEZY WINDS LIKELY IMPACTING RADIATIONAL COOLING EACH NIGHT. FORECAST IS STILL CALLING FOR UPPER 90S/LOW 100S EACH AFTERNOON..AND BY MON/TUE I WOULDNT BE SURPRISED IF WE SAW A FEW LOCATIONS COME WITHIN A FEW DEGREES OF RECORD HIGHS. .LONG TERM...(WEDNESDAY THROUGH SATURDAY) ISSUED AT 254 AM MDT SUN AUG 25 2013 MUCH OF THE SAME FOR THE SECOND HALF OF THIS WEEK WITH HOT AND DRY CONDITIONS CONTINUING. A BROAD H5 RIDGE CENTERED OVER KANSAS WILL BE WELL-ESTABLISHED BY MID-WEEK. THIS RIDGE WILL GRADUALLY BUILD WEST OVER THE REST OF THE WEEK...KEEPING THE SENSIBLE WX FAIRLY BENIGN. THE ONLY INTERESTING FEATURE IS A WEAK VORT MAX THAT MAY MOVE ACROSS EASTERN COLORADO INTO WESTERN KANSAS LATE THURSDAY. WHILE THERE WILL BE SOME UPPER-LEVEL MOISTURE...SOUNDINGS APPEAR TOO STABLE TO SUPPORT WIDESPREAD STORMS. THE OPERATIONAL GFS PRINTS OUT SOME QPF IN WESTERN KANSAS FROM THIS...AS WELL AS JUST ONE OF THE TWELVE ENSEMBLE PERTURBATIONS...SO HAVE LITTLE CONFIDENCE IN ANY PRECIP BEING REALIZED. RIDGE CONTINUES DRIFTING WESTWARD OVER THE WEEKEND WHILE AN UPPER LOW MOVING INTO THE PACIFIC NORTHWEST MAY HELP TO WEAKEN THE RIDGE LATE IN THE WEEKEND. FOR NOW...NO PRECIP CHANCES THROUGH SATURDAY AFTERNOON. FOR TEMPS...ALL GUIDANCE CONTINUES TO TREND WARMER FOR THE PERIOD WITH 850MB TEMPS IN THE LOW 30S C. TEMPS WILL BE NEARLY THE SAME EVERY DAY...HIGHS IN THE MID TO UPPER 90S AND LOWS IN THE MID 60S TO LOW 70S. HIGHS ARE NOT EXPECTED TO BE RECORD BREAKING...BUT A FEW STATIONS COULD APPROACH RECORD HIGHS ANY DAY OF THE EXTENDED. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING) ISSUED AT 529 AM MDT SUN AUG 25 2013 VFR CONDITIONS WILL CONTINUE THROUGH THE TAF PERIOD AT BOTH KGLD AND KMCK...WITH ONLY PASSING HIGH CLOUDS. BREEZY CONDITIONS WILL REDEVELOP THIS MORNING AND CONTINUE THROUGH AT LEAST THE EARLY EVENING HOURS...POSSIBLY INTO THE OVERNIGHT AS TIGHT PRESSURE GRADIENT REMAINS IN PLACE. STRONGEST WIND GUSTS WILL BE THIS AFTERNOON WHEN GUSTS 30-35KT WILL BE POSSIBLE AT BOTH TERMINALS. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...DR LONG TERM...JJM AVIATION...DR
AREA FORECAST DISCUSSION...CORRECTED
NWS DULUTH MN
729 AM CDT SUN AUG 25 2013 .AVIATION...12Z TAF ISSUANCE... STORMS WILL MOVE NEAR THE KHIB SITE EARLY MORNING SO HAVE INCLUDED A VCTS THRU 14Z. OTHERWISE VFR CONDITIONS ARE EXPECTED TODAY. A WEAK FRONT.. OR WINDSHIFT BDRY... WILL SINK SOUTH LATER TODAY FROM THE BORDERLAND TOWARDS THE TWIN PORTS. THUNDERSTORMS ARE POSSIBLE ALONG THIS BDRY LATER TODAY AND CONTINUING THIS EVENING. THERE IS A POSSIBILITY THAT THE CONVECTION MAY HAVE A TOUGH TIME INITIATING GIVEN THE EXTENT OF WARM AIR ALOFT. GIVEN LOWER CONFIDENCE IN CONVECTION WE WILL USE PROB 30 BEGINNING LATE TODAY AT KBRD/KDLH/KHYR TERMINALS. MAJORITY OF CONVECTION IS EXPECTED TO REMAIN SOUTH OF KINL THIS PERIOD. && .PREV DISCUSSION... /ISSUED 604 AM CDT SUN AUG 25 2013/ UPDATE... WE`VE HAD TO UPDATE GRIDS/PRODUCTS THIS MORNING TO ADD MORE SHOWERS/STORMS ACROSS THE NORTHLAND FOR THE NEXT FEW HOURS. RADAR HAS SHOWN AN INCREASE IN COVERAGE OVER CENTRAL MINNESOTA AND OVER CROW WING/AITKIN COUNTIES. SOME STRONG STORMS WILL REMAIN POSSIBLE FOR A COUPLE MORE HOURS. THE LATEST 08Z HRRR AS WELL AS THE NMM/ARW HIRES MODELS SUGGEST MUCH OF THESE SHOWERS/STORMS WILL DISSIPATE BY MID-LATE MORNING. HOWEVER...CONFIDENCE IN THIS OCCURRING IS LOWER THAN NORMAL SINCE THEY ARE NOT DOING A GOOD JOB WITH THE CURRENT CONVECTION. PREV DISCUSSION... /ISSUED 349 AM CDT SUN AUG 25 2013/ SHORT TERM...THROUGH EARLY MONDAY EVENING. HOT AND HUMID CONDITIONS WILL COVER MUCH OF THE NORTHLAND TODAY. THE LARGE UPPER HIGH OVER THE CENTRAL CONUS WILL REMAIN THROUGH THE SHORT TERM...WITH A COUPLE DIFFERENT FEATURES MOVING THROUGH BRINGING A THREAT FOR SHOWERS/STORMS. AS OF 0830Z...A FEW THUNDERSTORMS WERE OCCURRING OVER FAR NORTHERN MINNESOTA DUE TO A PASSING WAVE AND WAA WITH SOUTHWESTERLY LLJ. KDLH`S VWP SHOWED 35 KT AT 925MB WITH WEST WINDS AT 850MB OF 50 KT. STRONG THUNDERSTORMS WERE OCCURRING OVER EASTERN NORTH DAKOTA IN AN AREA OF LOW LEVEL CONVERGENCE ALONG A WEAK FRONTAL BOUNDARY. THE AIRMASS IS PLENTY UNSTABLE THIS MORNING WITH MUCAPES OF 1000-2000J/KG AND MLCAPES OF 500-1500J/KG. WARM LOW-MID LEVEL TEMPS COVERED THE CWA...WITH THE MODELS SHOWING 700MB TEMPS OF +10 TO +12C. THE 00Z KINL SOUNDING HAD +11C AT 700MB. WE EXPECT THE NORTHERN MINNESOTA SHOWERS/STORMS TO CONTINUE EAST EARLY THIS MORNING...WITH SOUTHWARD DEVELOPMENT LOOKING LESS LIKELY. THE LOW LEVEL CONVERGENT AREA AS FORECAST BY THE RAP AT 925MB...MAY ALLOW FOR SOME ADDITIONAL DEVELOPMENT OVER PORTIONS OF OUR WEST/SOUTHWEST PRIOR TO 12Z...BUT MORE LIKELY AFTER THAT TIME. THERE WILL BE A BATTLE BETWEEN THE LIFT FROM THE APPROACHING TROUGH AND THE WARM MID LEVEL TEMPS TODAY. WE DO KEEP SOME LOW POPS OVER CENTRAL PORTIONS OF THE CWA...THEN INCREASE FURTHER LATER THIS AFTERNOON WITH MAX HEATING...THE LOW LEVEL TROUGH AND PERHAPS A WEAK WAVE ALL CONTRIBUTING TO LIFT. THE STORMS COULD BE SEVERE OVER THE SOUTHERN HALF OF THE NORTHLAND THIS AFTERNOON INTO TONIGHT. WE STILL EXPECT HIGHS TO REACH THE LOWER TO MIDDLE NINETIES OVER MUCH OF THE NORTHLAND. IT WILL BE HUMID WITH DEWPOINTS IN THE UPPER SIXTIES TO LOWER SEVENTIES. WE KEPT THE HEAT ADVISORY THE SAME. AREAS AROUND LAKE SUPERIOR...EXCEPT FOR PERHAPS UP INTO COASTAL COOK COUNTY...WILL ALSO BE HOT TODAY DUE TO OFFSHORE WINDS. MONDAY WILL REMAIN HOT WITH HIGHS FROM THE UPPER EIGHTIES TO LOWER NINETIES. AREAS ALONG LAKE SUPERIOR WILL BE COOLER THOUGH...AS AN ONSHORE FLOW DEVELOPS DUE TO LOW PRESSURE OUT TO THE WEST AND A WEAK HIGH TO THE EAST. A WARM FRONT WILL BE DRAPED FROM WEST TO EAST ACROSS THE NORTHLAND. WE INTRODUCED SOME POPS ALONG THIS FEATURE OVER ALL BUT FAR NORTHERN MINNESOTA ON MONDAY. CONVERGENCE IS WEAK...BUT WE CAN`T RULE OUT SOME THUNDERSTORM DEVELOPMENT WITH PEAK HEATING. LONG TERM...MONDAY NIGHT THROUGH SUNDAY. A LARGE SFC/MID LVL RIDGE WILL PREVAIL OVER THE SRN PLAINS THROUGH THE WEEK WITH UNUSUALLY HOT AND MUGGY WEATHER EXPECTED ACROSS THE NORTHLAND. THE HEAT WILL BE TEMPERED BRIEFLY BY THE PASSAGE OF A FRONTAL SYSTEM MON NIGHT AND EARLY TUESDAY. THIS WILL BE THE BEST CHANCE FOR MUCH NEEDED PRECIP ACROSS THE CTRL/SRN CWA. HOWEVER...THE PRESENCE OF THE ANOMALOUS RIDGE AT MID LVLS WITH AN ASSOCIATED MID LVL WARM LAYER MAKES THE CONVECTIVE OPPORTUNITIES QUESTIONABLE. MOST LIKELY AREA WILL BE NRN MN ZONES AHEAD OF WARM FRONTAL BDRY MONDAY NIGHT AND ON NRN FRINGES OF NORTHWARD ADVECTING MID LVL CAP. SFC COLD FRONT WILL PASS THROUGH TUESDAY HOWEVER EXTENSIVE CIN IS EXPECTED BY EARLY AFTN SO POPS LOWERED. HIGH PRESSURE IS EXPECTED TO PASS ACROSS THE AREA WED/WED NIGHT. A TEMPORARY REDUCTION IN HUMIDITY SHOULD OCCUR BEFORE SFC HIGH MOVES EAST THURSDAY. HEAT/HUMIDITY INCREASE LATE WEEK INTO WEEKEND AS WARM ADVECTION RESUMES. LOW POPS LATE WEEK AND INTO WEEKEND AS UPPER JET REMAINS NORTH OF CWA AND MAIN CONVECTION CHANCES ARE POSITIONED NORTH AND WEST OF CWA. && .POINT TEMPS/POPS... DLH 92 69 89 68 / 40 50 20 50 INL 87 61 88 67 / 20 10 10 60 BRD 96 69 94 72 / 30 50 20 40 HYR 94 71 92 71 / 40 60 20 50 ASX 93 69 85 68 / 40 50 20 50 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...HEAT ADVISORY FROM 11 AM THIS MORNING TO 9 PM CDT MONDAY FOR MNZ033>038. WI...HEAT ADVISORY FROM 11 AM THIS MORNING TO 9 PM CDT MONDAY FOR WIZ001>004-006>009. LS...NONE. && $$ AVIATION...CANNON
AREA FORECAST DISCUSSION...UPDATED
NWS DULUTH MN
642 AM CDT SUN AUG 25 2013 .AVIATION...12Z TAF ISSUANCE... STORMS WILL MOVE NEAR THE KHIB SITE EARLY MORNING SO HAVE INCLUDED A VCTS THRU 14Z. OTHERWISE VFR CONDITIONS ARE EXPECTED TODAY. A WEAK FRONT.. OR WINDSHIFT BDRY... WILL SINK SOUTH LATER TODAY FROM THE BORDERLAND TOWARDS THE TWIN PORTS. THUNDERSTORMS ARE POSSIBLE ALONG THIS BDRY LATER TODAY AND CONTINUING THIS EVENING. THERE IS A POSSIBILITY THAT THE CONVECTION MAY HAVE A TOUGH TIME INITIATING GIVEN THE EXTENT OF WARM AIR ALOFT. GIVEN LOWER CONFIDENCE IN CONVECTION WE WILL USE PROB 30 BEGINNING LATE TODAY AT KBRD/KDLH/KHYR TERMINALS. MAJORITY OF CONVECTION IS EXPECTED TO REMAIN SOUTH OF KINL THIS PERIOD. && .PREV DISCUSSION... /ISSUED 604 AM CDT SUN AUG 25 2013/ UPDATE... WE`VE HAD TO UPDATE GRIDS/PRODUCTS THIS MORNING TO ADD MORE SHOWERS/STORMS ACROSS THE NORTHLAND FOR THE NEXT FEW HOURS. RADAR HAS SHOWN AN INCREASE IN COVERAGE OVER CENTRAL MINNESOTA AND OVER CROW WING/AITKIN COUNTIES. SOME STRONG STORMS WILL REMAIN POSSIBLE FOR A COUPLE MORE HOURS. THE LATEST 08Z HRRR AS WELL AS THE NMM/ARW HIRES MODELS SUGGEST MUCH OF THESE SHOWERS/STORMS WILL DISSIPATE BY MID-LATE MORNING. HOWEVER...CONFIDENCE IN THIS OCCURRING IS LOWER THAN NORMAL SINCE THEY ARE NOT DOING A GOOD JOB WITH THE CURRENT CONVECTION. PREV DISCUSSION... /ISSUED 349 AM CDT SUN AUG 25 2013/ SHORT TERM...THROUGH EARLY MONDAY EVENING. HOT AND HUMID CONDITIONS WILL COVER MUCH OF THE NORTHLAND TODAY. THE LARGE UPPER HIGH OVER THE CENTRAL CONUS WILL REMAIN THROUGH THE SHORT TERM...WITH A COUPLE DIFFERENT FEATURES MOVING THROUGH BRINGING A THREAT FOR SHOWERS/STORMS. AS OF 0830Z...A FEW THUNDERSTORMS WERE OCCURRING OVER FAR NORTHERN MINNESOTA DUE TO A PASSING WAVE AND WAA WITH SOUTHWESTERLY LLJ. KDLH`S VWP SHOWED 35 KT AT 925MB WITH WEST WINDS AT 850MB OF 50 KT. STRONG THUNDERSTORMS WERE OCCURRING OVER EASTERN NORTH DAKOTA IN AN AREA OF LOW LEVEL CONVERGENCE ALONG A WEAK FRONTAL BOUNDARY. THE AIRMASS IS PLENTY UNSTABLE THIS MORNING WITH MUCAPES OF 1000-2000J/KG AND MLCAPES OF 500-1500J/KG. WARM LOW-MID LEVEL TEMPS COVERED THE CWA...WITH THE MODELS SHOWING 700MB TEMPS OF +10 TO +12C. THE 00Z KINL SOUNDING HAD +11C AT 700MB. WE EXPECT THE NORTHERN MINNESOTA SHOWERS/STORMS TO CONTINUE EAST EARLY THIS MORNING...WITH SOUTHWARD DEVELOPMENT LOOKING LESS LIKELY. THE LOW LEVEL CONVERGENT AREA AS FORECAST BY THE RAP AT 925MB...MAY ALLOW FOR SOME ADDITIONAL DEVELOPMENT OVER PORTIONS OF OUR WEST/SOUTHWEST PRIOR TO 12Z...BUT MORE LIKELY AFTER THAT TIME. THERE WILL BE A BATTLE BETWEEN THE LIFT FROM THE APPROACHING TROUGH AND THE WARM MID LEVEL TEMPS TODAY. WE DO KEEP SOME LOW POPS OVER CENTRAL PORTIONS OF THE CWA...THEN INCREASE FURTHER LATER THIS AFTERNOON WITH MAX HEATING...THE LOW LEVEL TROUGH AND PERHAPS A WEAK WAVE ALL CONTRIBUTING TO LIFT. THE STORMS COULD BE SEVERE OVER THE SOUTHERN HALF OF THE NORTHLAND THIS AFTERNOON INTO TONIGHT. WE STILL EXPECT HIGHS TO REACH THE LOWER TO MIDDLE NINETIES OVER MUCH OF THE NORTHLAND. DULUTH MAY BREAK IT`S RECORD HIGH FOR THE DATE...WHICH IS 90...AND INTERNATIONAL FALLS WILL BE CLOSE WITH IT`S RECORD HIGH TODAY OF 92. IT WILL BE HUMID WITH DEWPOINTS IN THE UPPER SIXTIES TO LOWER SEVENTIES. WE KEPT THE HEAT ADVISORY THE SAME. AREAS AROUND LAKE SUPERIOR...EXCEPT FOR PERHAPS UP INTO COASTAL COOK COUNTY...WILL ALSO BE HOT TODAY DUE TO OFFSHORE WINDS. MONDAY WILL REMAIN HOT WITH HIGHS FROM THE UPPER EIGHTIES TO LOWER NINETIES. AREAS ALONG LAKE SUPERIOR WILL BE COOLER THOUGH...AS AN ONSHORE FLOW DEVELOPS DUE TO LOW PRESSURE OUT TO THE WEST AND A WEAK HIGH TO THE EAST. A WARM FRONT WILL BE DRAPED FROM WEST TO EAST ACROSS THE NORTHLAND. WE INTRODUCED SOME POPS ALONG THIS FEATURE OVER ALL BUT FAR NORTHERN MINNESOTA ON MONDAY. CONVERGENCE IS WEAK...BUT WE CAN`T RULE OUT SOME THUNDERSTORM DEVELOPMENT WITH PEAK HEATING. LONG TERM...MONDAY NIGHT THROUGH SUNDAY. A LARGE SFC/MID LVL RIDGE WILL PREVAIL OVER THE SRN PLAINS THROUGH THE WEEK WITH UNUSUALLY HOT AND MUGGY WEATHER EXPECTED ACROSS THE NORTHLAND. THE HEAT WILL BE TEMPERED BRIEFLY BY THE PASSAGE OF A FRONTAL SYSTEM MON NIGHT AND EARLY TUESDAY. THIS WILL BE THE BEST CHANCE FOR MUCH NEEDED PRECIP ACROSS THE CTRL/SRN CWA. HOWEVER...THE PRESENCE OF THE ANOMALOUS RIDGE AT MID LVLS WITH AN ASSOCIATED MID LVL WARM LAYER MAKES THE CONVECTIVE OPPORTUNITIES QUESTIONABLE. MOST LIKELY AREA WILL BE NRN MN ZONES AHEAD OF WARM FRONTAL BDRY MONDAY NIGHT AND ON NRN FRINGES OF NORTHWARD ADVECTING MID LVL CAP. SFC COLD FRONT WILL PASS THROUGH TUESDAY HOWEVER EXTENSIVE CIN IS EXPECTED BY EARLY AFTN SO POPS LOWERED. HIGH PRESSURE IS EXPECTED TO PASS ACROSS THE AREA WED/WED NIGHT. A TEMPORARY REDUCTION IN HUMIDITY SHOULD OCCUR BEFORE SFC HIGH MOVES EAST THURSDAY. HEAT/HUMIDITY INCREASE LATE WEEK INTO WEEKEND AS WARM ADVECTION RESUMES. LOW POPS LATE WEEK AND INTO WEEKEND AS UPPER JET REMAINS NORTH OF CWA AND MAIN CONVECTION CHANCES ARE POSITIONED NORTH AND WEST OF CWA. && .POINT TEMPS/POPS... DLH 92 69 89 68 / 40 50 20 50 INL 87 61 88 67 / 20 10 10 60 BRD 96 69 94 72 / 30 50 20 40 HYR 94 71 92 71 / 40 60 20 50 ASX 93 69 85 68 / 40 50 20 50 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...HEAT ADVISORY FROM 11 AM THIS MORNING TO 9 PM CDT MONDAY FOR MNZ033>038. WI...HEAT ADVISORY FROM 11 AM THIS MORNING TO 9 PM CDT MONDAY FOR WIZ001>004-006>009. LS...NONE. && $$ AVIATION...CANNON
AREA FORECAST DISCUSSION
NWS DULUTH MN
604 AM CDT SUN AUG 25 2013 .UPDATE... WE`VE HAD TO UPDATE GRIDS/PRODUCTS THIS MORNING TO ADD MORE SHOWERS/STORMS ACROSS THE NORTHLAND FOR THE NEXT FEW HOURS. RADAR HAS SHOWN AN INCREASE IN COVERAGE OVER CENTRAL MINNESOTA AND OVER CROW WING/AITKIN COUNTIES. SOME STRONG STORMS WILL REMAIN POSSIBLE FOR A COUPLE MORE HOURS. THE LATEST 08Z HRRR AS WELL AS THE NMM/ARW HIRES MODELS SUGGEST MUCH OF THESE SHOWERS/STORMS WILL DISSIPATE BY MID-LATE MORNING. HOWEVER...CONFIDENCE IN THIS OCCURRING IS LOWER THAN NORMAL SINCE THEY ARE NOT DOING A GOOD JOB WITH THE CURRENT CONVECTION. && .PREV DISCUSSION... /ISSUED 349 AM CDT SUN AUG 25 2013/ SHORT TERM...THROUGH EARLY MONDAY EVENING. HOT AND HUMID CONDITIONS WILL COVER MUCH OF THE NORTHLAND TODAY. THE LARGE UPPER HIGH OVER THE CENTRAL CONUS WILL REMAIN THROUGH THE SHORT TERM...WITH A COUPLE DIFFERENT FEATURES MOVING THROUGH BRINGING A THREAT FOR SHOWERS/STORMS. AS OF 0830Z...A FEW THUNDERSTORMS WERE OCCURRING OVER FAR NORTHERN MINNESOTA DUE TO A PASSING WAVE AND WAA WITH SOUTHWESTERLY LLJ. KDLH`S VWP SHOWED 35 KT AT 925MB WITH WEST WINDS AT 850MB OF 50 KT. STRONG THUNDERSTORMS WERE OCCURRING OVER EASTERN NORTH DAKOTA IN AN AREA OF LOW LEVEL CONVERGENCE ALONG A WEAK FRONTAL BOUNDARY. THE AIRMASS IS PLENTY UNSTABLE THIS MORNING WITH MUCAPES OF 1000-2000J/KG AND MLCAPES OF 500-1500J/KG. WARM LOW-MID LEVEL TEMPS COVERED THE CWA...WITH THE MODELS SHOWING 700MB TEMPS OF +10 TO +12C. THE 00Z KINL SOUNDING HAD +11C AT 700MB. WE EXPECT THE NORTHERN MINNESOTA SHOWERS/STORMS TO CONTINUE EAST EARLY THIS MORNING...WITH SOUTHWARD DEVELOPMENT LOOKING LESS LIKELY. THE LOW LEVEL CONVERGENT AREA AS FORECAST BY THE RAP AT 925MB...MAY ALLOW FOR SOME ADDITIONAL DEVELOPMENT OVER PORTIONS OF OUR WEST/SOUTHWEST PRIOR TO 12Z...BUT MORE LIKELY AFTER THAT TIME. THERE WILL BE A BATTLE BETWEEN THE LIFT FROM THE APPROACHING TROUGH AND THE WARM MID LEVEL TEMPS TODAY. WE DO KEEP SOME LOW POPS OVER CENTRAL PORTIONS OF THE CWA...THEN INCREASE FURTHER LATER THIS AFTERNOON WITH MAX HEATING...THE LOW LEVEL TROUGH AND PERHAPS A WEAK WAVE ALL CONTRIBUTING TO LIFT. THE STORMS COULD BE SEVERE OVER THE SOUTHERN HALF OF THE NORTHLAND THIS AFTERNOON INTO TONIGHT. WE STILL EXPECT HIGHS TO REACH THE LOWER TO MIDDLE NINETIES OVER MUCH OF THE NORTHLAND. DULUTH MAY BREAK IT`S RECORD HIGH FOR THE DATE...WHICH IS 90...AND INTERNATIONAL FALLS WILL BE CLOSE WITH IT`S RECORD HIGH TODAY OF 92. IT WILL BE HUMID WITH DEWPOINTS IN THE UPPER SIXTIES TO LOWER SEVENTIES. WE KEPT THE HEAT ADVISORY THE SAME. AREAS AROUND LAKE SUPERIOR...EXCEPT FOR PERHAPS UP INTO COASTAL COOK COUNTY...WILL ALSO BE HOT TODAY DUE TO OFFSHORE WINDS. MONDAY WILL REMAIN HOT WITH HIGHS FROM THE UPPER EIGHTIES TO LOWER NINETIES. AREAS ALONG LAKE SUPERIOR WILL BE COOLER THOUGH...AS AN ONSHORE FLOW DEVELOPS DUE TO LOW PRESSURE OUT TO THE WEST AND A WEAK HIGH TO THE EAST. A WARM FRONT WILL BE DRAPED FROM WEST TO EAST ACROSS THE NORTHLAND. WE INTRODUCED SOME POPS ALONG THIS FEATURE OVER ALL BUT FAR NORTHERN MINNESOTA ON MONDAY. CONVERGENCE IS WEAK...BUT WE CAN`T RULE OUT SOME THUNDERSTORM DEVELOPMENT WITH PEAK HEATING. LONG TERM...MONDAY NIGHT THROUGH SUNDAY. A LARGE SFC/MID LVL RIDGE WILL PREVAIL OVER THE SRN PLAINS THROUGH THE WEEK WITH UNUSUALLY HOT AND MUGGY WEATHER EXPECTED ACROSS THE NORTHLAND. THE HEAT WILL BE TEMPERED BRIEFLY BY THE PASSAGE OF A FRONTAL SYSTEM MON NIGHT AND EARLY TUESDAY. THIS WILL BE THE BEST CHANCE FOR MUCH NEEDED PRECIP ACROSS THE CTRL/SRN CWA. HOWEVER...THE PRESENCE OF THE ANOMALOUS RIDGE AT MID LVLS WITH AN ASSOCIATED MID LVL WARM LAYER MAKES THE CONVECTIVE OPPORTUNITIES QUESTIONABLE. MOST LIKELY AREA WILL BE NRN MN ZONES AHEAD OF WARM FRONTAL BDRY MONDAY NIGHT AND ON NRN FRINGES OF NORTHWARD ADVECTING MID LVL CAP. SFC COLD FRONT WILL PASS THROUGH TUESDAY HOWEVER EXTENSIVE CIN IS EXPECTED BY EARLY AFTN SO POPS LOWERED. HIGH PRESSURE IS EXPECTED TO PASS ACROSS THE AREA WED/WED NIGHT. A TEMPORARY REDUCTION IN HUMIDITY SHOULD OCCUR BEFORE SFC HIGH MOVES EAST THURSDAY. HEAT/HUMIDITY INCREASE LATE WEEK INTO WEEKEND AS WARM ADVECTION RESUMES. LOW POPS LATE WEEK AND INTO WEEKEND AS UPPER JET REMAINS NORTH OF CWA AND MAIN CONVECTION CHANCES ARE POSITIONED NORTH AND WEST OF CWA. AVIATION...06Z TAF ISSUANCE. VFR CONDITIONS WILL PREVAIL MOST OF THE FCST PERIOD EXCEPT IN THE NRN TIER OF MN WHERE LOCAL MVFR/IFR MAY OCCUR IN LOWER CLOUD DEVELOPMENT AND HEAVIER STORMS EARLY THIS MORNING. A WEAK SFC BDRY WILL TRY TO PUSH SOUTH ACROSS THE AREA TODAY. MID LVL WARMTH SHOULD MAKE CONVECTION TOUGH TO DEVELOP. AMENDMENTS MAY BE REQUIRED GIVEN UNCERTAINTY OF CONVECTIVE DEVELOPMENT. LLWS AT KBRD/KHYR AS 45/50KT LLJ TRANSLATES EAST THROUGH 12Z. && .POINT TEMPS/POPS... DLH 92 69 89 68 / 40 50 20 50 INL 87 61 88 67 / 20 10 10 60 BRD 96 69 94 72 / 30 50 20 40 HYR 94 71 92 71 / 40 60 20 50 ASX 93 69 85 68 / 40 50 20 50 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...HEAT ADVISORY FROM 11 AM THIS MORNING TO 9 PM CDT MONDAY FOR MNZ033>038. WI...HEAT ADVISORY FROM 11 AM THIS MORNING TO 9 PM CDT MONDAY FOR WIZ001>004-006>009. LS...NONE. && $$ SHORT TERM...MELDE LONG TERM....CANNON
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1001 AM CDT SUN AUG 25 2013 .UPDATE... ISSUED AT 1000 AM CDT SUN AUG 25 2013 WEAK HIGH PRESSURE PATTERN OVER THE STATE THIS MORNING WITH A WEAK TROUGH OF LOW PRESSURE LINGERING ACROSS SOUTH CENTRAL AND SOUTHEAST NORTH DAKOTA. THIS COULD BE THE FOCUS FOR AN ISOLATED THUNDERSTORM THIS MORNING. WILL RE EVALUATE THE POTENTIAL FOR THE AFTERNOON...FOR NOW LEFT A SLIGHT CHANCE THUNDERSTORMS SOUTHEAST THIS MORNING WHERE HRRR MODEL GENERATES ISOLATED CONVECTION. ARE OF CLOUDS IN CENTRAL/EASTERN MONTANA APPEAR TO BE ASSOCIATED WITH A SHORT WAVE CENTERED IN WESTERN WYOMING MOVING NORTHEAST. THE RIDGE MAY PREVENT THE CLOUDS AND SHOWERS/THUNDERSTORMS FROM MAKING MUCH EASTWARD ADVANCEMENT INTO WESTERN NORTH DAKOTA THIS AFTERNOON... ALTHOUGH NEW NAM GENERATES SOME THUNDERSTORMS AFTER 3 PM. DON`T HAVE ENOUGH CONFIDENCE TO MOVE UP THE TIME TABLE FORM THIS EVENING INTO THE IS AFTERNOON. UPDATE ISSUED AT 644 AM CDT SUN AUG 25 2013 MAINLY CLEAR SKIES ACROSS WESTERN AND CENTRAL NORTH DAKOTA THIS MORNING. HIGH PRESSURE OVER THE WEST WITH DRIER AIR WORKING INTO THE AREA ALLOWED TEMPERATURES TO FALL INTO THE LOWER TO MIDDLE 50S. MEANWHILE A LOW PRESSURE TROUGH REMAINS FROM CENTRAL SOUTH DAKOTA INTO EAST CENTRAL NORTH DAKOTA WITH MUCH HIGHER HUMIDITIES. TEMPERATURES HERE HAVE ONLY FALLEN INTO THE UPPER 60S AND LOWER 70S. NO SIGNIFICANT CHANGES TO THE FORECAST THIS UPDATE. DID KEEP A SLIGHT CHANCE OF THUNDER OVER THE SOUTHEAST NEAR THE WEAK SURFACE TROUGH. LATEST 06 UTC NAM IS INDICATING LIGHT QPF ENTERING INTO THE WEST LATER THIS AFTERNOON. WILL LEAVE THIS OUT OF THE FORECAST FOR NOW BUT WILL LET THE DAY SHIFT MONITOR. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 303 AM CDT SUN AUG 25 2013 MAIN HIGHLIGHT IN THE SHORT TERM WILL BE ANOTHER HOT DAY WITH HIGHS WELL INTO THE 90S...HOWEVER THUNDERSTORMS WILL BE CONFINED TO FAR SOUTH CENTRAL NORTH DAKOTA AND THE SOUTHERN JAMES RIVER VALLEY. EARLY THIS MORNING...THE LATEST LOCAL RADAR SHOWS A LINE OF SHOWERS AND THUNDERSTORMS INITIATING ALONG A FRONTAL BOUNDARY/LOW CONVERGENCE ZONE...STRETCHING FROM CORSON COUNTY IN SOUTH DAKOTA NORTHEAST BETWEEN BURLEIGH AND EMMONS COUNTY AND INTO STUTSMAN COUNTY. WATER VAPOR INDICATIVE OF A SHORTWAVE MOVING THROUGH CENTRAL NORTH DAKOTA EARLY THIS MORNING PROVIDING THE LIFT NEEDED TO SUSTAIN AND REDEVELOP THE PRECIPITATION. A COUPLE OF THE THUNDERSTORMS HAVE COME CLOSE TO SEVERE CRITERIA...AND WILL CONTINUE TO MONITOR. FOR TODAY...UPPER LEVEL RIDGING CENTERED OVER CENTRAL KANSAS COMBINED WITH AN UPPER TROUGH ALONG THE WEST COAST...WILL MAINTAIN A SOUTHWEST FLOW INTO NORTH DAKOTA. A COUPLE OF SHORTWAVES ARE FORECAST TO SLIDE ACROSS THE NORTHERN BORDER WITH LITTLE OR NO AFFECT IN TERMS OF PRECIPITATION. THE AFOREMENTIONED FRONTAL BOUNDARY IS FORECAST TO SHIFT A BIT FURTHER SOUTH TODAY...INTO NORTHERN SOUTH DAKOTA. HOWEVER A SHORTWAVE MOVING OUT FROM COLORADO IS FORECAST TO MOVE INTO CENTRAL SOUTH DAKOTA THIS AFTERNOON. THIS SHOULD LEAD TO ISOLATED THUNDERSTORMS IN OUR SOUTHEAST ZONES CLOSEST TO THE FRONT. ELSEWHERE EXPECT MOSTLY SUNNY...DRY..AND HOT CONDITIONS WITH HIGHS 90F TO 98F. HEAT INDICES ARE FORECAST IN THE MID TO UPPER 90S IN OUR SOUTH CENTRAL ZONES AND WILL CONTINUE TO MENTION THIS IN THE HAZARDOUS WEATHER OUTLOOK. FOR SUNDAY NIGHT...LEE SIDE TROUGH DEVELOPS IN SOUTHEAST MONTANA AS A COUPLE OF SHORTWAVES ARRIVE VIA THE SOUTHWEST FLOW INTO WESTERN NORTH DAKOTA. HAVE MENTIONED ISOLATED THUNDERSTORMS WEST SUNDAY NIGHT WITH DRY CONDITIONS CENTRAL. LOWS WILL AGAIN BE IN THE 60S. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 303 AM CDT SUN AUG 25 2013 MAIN FORECAST ISSUES IN THE LONG TERM WILL BE DAYTIME HIGH TEMPERATURES AND PERIODIC THUNDERSTORM CHANCES. THERE IS A CONTINUED GOOD AGREEMENT AMONG BOTH THE ENSEMBLE AND DETERMINISTIC MODELS IN THE MEAN UPPER LEVEL FLOW WHICH FEATURES A STRONG RIDGE OVER THE CENTRAL U.S. THAT RETROGRADES FROM THE MISSOURI VALLEY WEST INTO THE SOUTHERN PLAINS THROUGH THE PERIOD. NORTH DAKOTA WILL REMAIN NEAR THE APEX OF THE RIDGE THROUGH THE WHICH WILL CONTINUE TO INDICATE VERY WARM DAYTIME HIGH TEMPERATURES. SOUTHERN PORTIONS OF THE CWA COULD FLIRT WITH HEAT ADVISORY CRITERIA ON MONDAY AND AGAIN LATER IN THE WEEK. IN ADDITION... ALMOST DAILY THUNDERSTORM CHANCES CAN BE EXPECTED WITH HIGH CAPES EVERY DAY BUT A STRONG CAP LIMITING CONVECTION. THE DETERMINISTIC MODELS CONTINUE TO ADVERTISE A FEW...MORE SIGNIFICANT...WAVES WORKING THROUGH THE MEAN RIDGE AND BRINGING BETTER PRECIPITATION CHANCES. ON MONDAY THE ECMWF/GEM APPEAR STRONGER WITH A WAVE MOVING INTO NORTH DAKOTA AND BRING QPF ACROSS THE NORTH. THE SOUTH WILL LIKELY REMAIN CAPPED UNDER WARM MID LEVEL TEMPERATURES. THE GFS IS STRONGER WITH THE RIDGING OVER THE AREA AND KEEPS PRECIPITATION MAINLY NORTH OF THE BORDER. WAVES CONTINUE TO WORK THROUGH THE MEAN RIDGE ON WEDNESDAY THROUGH FRIDAY BUT TIMING AND PLACEMENT DIFFERENCES INCREASE WITH LESS CONSENSUS BETWEEN THE MODELS EXISTS THAN THE MODEL RUNS FROM 24 HOURS AGO. THEREFORE WILL CONTINUE TO UTILIZE A BLENDED SOLUTION FOR PRECIPITATION. MODELS DO INDICATE AT LEAST A TEMPORARY BREAKDOWN OF THE UPPER RIDGE LATE IN THE PERIOD WITH THE ECMWF A GOOD 18 TO 24 HOURS QUICKER TO BRING PRECIPITATION CHANCES AND COOLER TEMPERATURES TO THE AREA. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING) ISSUED AT 1000 AM CDT SUN AUG 25 2013 AT 9 AM CDT...WEAK REGION OF HIGH PRESSURE COVERED NORTH DAKOTA. SKIES WERE CLEAR AND VFR CONDITIONS PREVAILED. LITTLE WILL CHANGE TODAY AS VFR IS EXPECTED TO CONTINUE. SCATTERED SHOWERS AND THUNDERSTORMS ARE FORECAST TO MOVE INTO WESTERN NORTH DAKOTA LATE THIS EVENING AND OVERNIGHT. SOME THUNDERSTORMS MAY IMPACT KISN- KDIK AFTER 08Z/3 AM USING THE VCTS TO DESCRIBE THE THREAT. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...WAA SHORT TERM...KS LONG TERM...TWH AVIATION...WAA
AREA FORECAST DISCUSSION
NWS TULSA OK
904 AM CDT SUN AUG 25 2013 .DISCUSSION... ANOTHER HOT AND HUMID DAY IS IN STORE FOR EASTERN OKLAHOMA AND NORTHWEST ARKANSAS WITH MID/UPPER RIDGING IN CONTROL. 12Z UPPER AIR DATA INDICATES 500MB HEIGHTS ARE RISING AND SOME 700MB MOISTURE REMAINS AT LITTLE ROCK...SHREVEPORT AND FORT WORTH. THIS WOULD SUGGEST THE BEST POTENTIAL FOR ISOLATED AFTERNOON SHOWERS/STORMS WILL BE OVER THE HIGH TERRAIN OF SOUTHEAST OKLAHOMA AND/OR WEST CENTRAL ARKANSAS AND DOWN NEAR THE RED RIVER. COVERAGE OF PRECIP YESTERDAY WAS VERY LOW...AND WITH THE RISING UPPER HEIGHTS THAT WILL LIKELY NOT CHANGE TODAY. THE LATEST HRRR SHOWS HINTS OF ISOLATED DEVELOPMENT DOWN IN THAT REGION. WILL ELECT TO CARRY SILENT 10 POPS THERE...AND WILL MONITOR THE CU FIELD LATER TODAY TO SEE IF AN INCREASE IS WARRANTED IN SPOTS. LACY && .PREV DISCUSSION... /ISSUED 320 AM CDT SUN AUG 25 2013/ DISCUSSION... A LARGE UPPER RIDGE WILL REMAIN PARKED OVER THE AREA THROUGH THE ENTIRE FORECAST PERIOD. THE GFS IS QUICKER THAN THE ECMWF TO BEGIN TO BREAK DOWN THE RIDGE NEXT WEEKEND INTO THE FIRST WEEK OF SEPTEMBER WHICH IS A REVERSAL FROM MODEL RUNS A COUPLE DAYS AGO. IN THE MEANTIME...HOT WEATHER WITH VERY LITTLE CHANCE OF RAIN WILL PREVAIL. TEMPERATURES WILL SLOWLY INCH UP LATER THIS WEEK...LIKELY PEAKING ON FRIDAY OR SATURDAY. STAYED CLOSE TO GUIDANCE TEMPERATURES THE NEXT FEW DAYS. && .PRELIMINARY POINT TEMPS/POPS... TUL 94 74 94 72 / 0 0 0 0 FSM 94 73 94 71 / 10 0 0 0 MLC 94 73 94 71 / 10 10 10 0 BVO 93 69 93 67 / 0 0 0 0 FYV 91 67 91 65 / 10 0 0 0 BYV 91 68 91 66 / 0 0 0 0 MKO 93 72 93 70 / 0 0 0 0 MIO 91 71 91 69 / 0 0 0 0 F10 93 73 93 71 / 0 0 0 0 HHW 96 73 96 71 / 10 10 10 0 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...NONE. AR...NONE. && $$ SHORT TERM...30
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
653 AM CDT SUN AUG 25 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 330 AM CDT SUN AUG 25 2013 MAIN FORECAST CONCERNS ARE ON TEMPERATURES TODAY AND THUNDERSTORM POTENTIAL TONIGHT. ...CURRENTLY AS OF 08Z... WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED TROUGHING ALONG THE WEST COAST OF NORTH AMERICA AND STRONG SUBTROPICAL RIDGING ENCOMPASSING KANSAS AND MISSOURI. AROUND THE RIDGING... MONSOONAL MOISTURE AND SHORTWAVES WERE EMANATING FROM BAJA CALIFORNIA / WHERE TROPICAL DEPRESSION IVO WAS LOCATED / NORTH- NORTHEAST INTO THE DAKOTAS. ONE SUCH MONSOONAL SHORTWAVE...ENHANCED BY CONVECTION...WAS TRACKING ACROSS NORTHERN ONTARIO. THE CONVECTION WITH THIS SHORTWAVE EXTENDS SOUTH INTO NORTHERN MN AND UPPER MI...BEING FED WITH MOISTURE BY A 35-50KT 850MB JET SEEN ON VWP AND PROFILER DATA EXTENDING FROM NEBRASKA INTO WESTERN LAKE SUPERIOR. EVEN A FEW STRAY SHOWERS EXTEND SOUTH INTO TREMPEALEAU COUNTY. REGARDING THE MOISTURE...GOES DERIVED PRECIPITABLE WATER IMAGERY SHOWED VALUES OF 1.5-2 INCHES ACROSS MUCH OF THE UPPER MIDWEST. THE CONVECTION IS ALSO RIDING ALONG THE EDGE OF A HOT AIRMASS ENCOMPASSING THE CENTRAL AND NORTHERN PLAINS AS WELL AS THE UPPER MIDWEST. RAP SHOWED 700MB TEMPS OF 12C OR HIGHER FROM DULUTH MN BACK INTO WESTERN NEBRASKA. MEANWHILE...DOWN AT 850MB...READINGS RANGED FROM 20-22C OVER THE FORECAST AREA TO 26-28C IN SOUTH DAKOTA. THE WARM AIRMASS EXTENDS DOWN TO THE SURFACE...WHERE OVER THE FORECAST AREA...A SOUTH BREEZE AND DEWPOINTS IN THE UPPER 60S TO LOW 70S HAS KEPT TEMPS AT OR ABOVE 70F. ALSO OF NOTE AT THE SURFACE IS A LOW PRESSURE TROUGH FROM INTERNATIONAL FALLS MN SOUTHWEST TO PHILLIP SOUTH DAKOTA. ...HAZARDS... 1. HEAT ADVISORY REMAINS ON TRACK FOR TODAY AND IN FACT HEAT INDICES MAY END UP HIGHER. 2. POTENTIAL CONVECTION TONIGHT COULD POSE A SEVERE RISK... PRIMARILY NORTH OF I-90. ISOLATED LARGE HAIL AND DAMAGING WINDS MAIN HAZARDS. ...SYNOPTIC OVERVIEW... 25.00Z MODELS ARE IN VERY GOOD AGREEMENT SHOWING THAT A WEAK 500MB RIDGE AXIS PRESENT ACROSS MN WILL FLATTEN OUT TODAY...THEN REBUILDS OVER THE DAKOTAS AHEAD OF A MORE DYNAMIC SHORTWAVE LIFTING OUT OF ARIZONA INTO WYOMING. WITHIN THE 500MB FLOW...MODELS SUGGEST A MONSOONAL SHORTWAVE SOMEWHERE IN NORTHWEST COLORADO OR EASTERN WYOMING CURRENTLY TO CROSS CENTRAL MN AND NORTHERN WI TONIGHT. ...DETAILS... THE FLATTENING OF THE 500MB FLOW TODAY WILL HELP TO SPREAD MORE OF THE WARMTH SEEN OVER SOUTH DAKOTA EASTWARD. 850MB TEMPS CLIMB TO 21-23C WHILE DOWN AT 925MB THEY JUMP TO 26-28C. MIXING TO THE 850MB TEMPS WHICH SEEMS QUITE REASONABLE GIVEN THAT WE SHOULD HAVE FULL SUN AND A BREEZY SOUTHWEST WIND YIELDS HIGHS IN THE LOW TO MID 90S. NOTICED THAT THE RAP IS EVEN WARMER...SUGGESTING HIGHS OF 95-100. THE REASON IS DUE TO SUPERADIABATIC EFFECTS...WHICH LOOK A BIT OVERDONE. WITH DEWPOINTS HOVERING IN THE UPPER 60S TO LOWER 70S ALL DAY...HEAT INDICES SHOULD TOP OUT BETWEEN 97-102. NOW THE BIGGER QUESTION IS CONVECTION CHANCES FOR LATE THIS AFTERNOON INTO TONIGHT. A COUPLE OF SCENARIOS EXIST... 1. THE 25.00Z NAM QUICKLY ERODES THE CAP BETWEEN 18-21Z FROM DULUTH INTO WESTERN UPPER MI...PERHAPS CAUSED BY AN OUTFLOW BOUNDARY EMANATING FROM CURRENT CONVECTION TRACKING ACROSS LAKE SUPERIOR. THIS CONVECTION THEN DIVES SOUTH INTO NORTHERN SECTIONS OF THE FORECAST AREA DURING THE EVENING INTO THE 850MB MOISTURE TRANSPORT AXIS...FOLLOWING CORFIDI VECTORS. THE CONVECTION EVENTUALLY WANES AFTER MIDNIGHT AS THE CAP RESTRENGTHENS. CONCERNED THAT THE NAM...IN PARTICULAR ITS BMJ CONVECTIVE SCHEME...MAY BE ERODING THE CAP TOO QUICKLY. 2. THE 25.00Z GFS...24.12Z ECMWF...THE BULK OF THE 25.03Z SREF MEMBERS AND 25.00Z HIRES-ARW GENERALLY WAIT TO BREAK OUT CONVECTION UNTIL AFTER 00Z ACROSS CENTRAL MN INTO NORTHERN WI...WHICH THEN DROPS SOUTH MORE INTO THE FORECAST AREA AFTER 06Z. AGAIN THE CONVECTION DIVES INTO THE 850MB MOISTURE TRANSPORT AXIS...FOLLOWING CORFIDI VECTORS. ADDITIONALLY...THESE MODELS SUGGEST THAT SHORTWAVE COMING OUT OF NORTHWEST COLORADO AND EASTERN WYOMING COULD BE AN ENHANCING PLAYER. 3. THE 24.12Z HIRES-ARW...25.00Z CANADIAN...UKMET AND ECMWF HAVE THE ONLY CONVECTION OCCURRING ACROSS NORTHERN WI AND UPPER MI TONIGHT... ON THE NOSE OF THE 850MB MOISTURE TRANSPORT. THEY SUGGESTS THE CAP HOLDS FOR LATE THIS AFTERNOON THROUGH TONIGHT...DIFFERENT FROM EITHER OF THE ABOVE 2 SCENARIOS. WHICH OF THE ABOVE 3 SCENARIOS PANS OUT BASICALLY DEPENDS ON THE STRENGTH OF THE CAP. FOR NOW LEANED TOWARDS SCENARIO NUMBER 2 AS IT HAS THE STRONGEST CONSENSUS...THOUGH CANNOT COMPLETELY RULE OUT NUMBER 3. THEREFORE...HAVE LIMITED PRECIPITATION CHANCES TO NO MORE THAN 50. THE SECOND SCENARIO ALSO POSES A MARGINAL SEVERE RISK NORTH OF I-90...GIVEN 0-6 KM SHEAR VALUES REACHING 25-30 KT AND STRONG INSTABILITY. MULTICELLS SEEM TO BE THE MOST LIKELY STORM MODE. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 330 AM CDT SUN AUG 25 2013 ...HAZARDS... 1. HEAT. HEAT ADVISORIES CONTINUE TO LOOK SOLID FOR MONDAY AND TUESDAY...AND THERE IS EVEN SOME CONCERN WE MAY HAVE TO UPGRADE PORTIONS OF THE AREA TO EXCESSIVE HEAT WARNING ON TUESDAY. THE ADVISORY MAY ALSO HAVE TO BE EXTENDED INTO WEDNESDAY SOUTH OF I-90. ANOTHER ROUND OF HEAT HAZARDS ARE POSSIBLE FOR LABOR DAY WEEKEND. 2. STORMS. POTENTIAL FOR SOME SEVERE WEATHER MONDAY NIGHT IF THE 25.00Z NAM/GFS ARE CORRECT WITH ANOTHER THUNDERSTORM COMPLEX MOVING THROUGH. ISOLATED LARGE HAIL AND DAMAGING WINDS MAIN HAZARDS. ...SYNOPTIC OVERVIEW... THE SUBTROPICAL HIGH CENTERED OVER KANSAS AND MISSOURI REMAINS PROGGED TO RETROGRADE WESTWARD TO SIT MOSTLY OVER KANSAS FOR TUESDAY THROUGH THURSDAY. THIS RETROGRESSION IS CAUSED BY DEEPER TROUGHING GRADUALLY FORMING OVER NEW ENGLAND. WHAT HAS BEEN PROBLEMATIC IS AFTER THURSDAY. 24.12Z ECMWF KEPT A NORTHWEST FLOW PATTERN GOING OVER THE FORECAST AREA FOR FRIDAY AND SATURDAY AS THE TROUGH PERSISTS IN NEW ENGLAND. HOWEVER...THE NEW 25.00Z ECMWF GOES ALONG WITH THE 25.00Z GFS TO ALLOW THE SUBTROPICAL HIGH AND ASSOCIATED RIDGING TO SHIFT EAST QUICKER. THIS MEANS THAT HEAT ISSUES ARE MORE LIKELY FOR LABOR DAY WEEKEND. ...PRECIPITATION DETAILS... ALL INDICATIONS ARE THAT SHOULD CONVECTION FROM TONIGHT SHOULD WEAKEN MONDAY MORNING DUE TO DIMINISHING MOISTURE TRANSPORT. MAINTAINED 20-40 PERCENT CHANCES MAINLY ACROSS WI FOR THE CONVECTION. THESE CHANCES SHIFT TO NORTH OF I-94 FOR THE AFTERNOON WHERE THE REMNANT OUTFLOW/WARM FRONTAL BOUNDARY MAY SERVE AS A TRIGGER FOR RENEWED CONVECTIVE DEVELOPMENT. OF COURSE...SHOULD THE UKMET/CANADIAN/ECMWF PAN OUT...MONDAY WILL BE DRY. 20-40 PERCENT CHANCES CONTINUE MONDAY NIGHT AND TUESDAY...GENERALLY ALONG AND NORTH OF I-94...WHERE ANOTHER THUNDERSTORM COMPLEX MAY SLIDE ACROSS AS INDICATED BY THE 25.00Z NAM/GFS. THESE STORMS WILL ALSO HAVE THAT STRONGER SHORTWAVE LIFTING OUT OF WYOMING AT 12Z MONDAY...HEADING INTO CENTRAL/NORTHERN MN BY 12Z TUESDAY FORCING IT. NOTE THAT THE 25.00Z ECMWF/CANADIAN/UKMET ARE FARTHER NORTH WITH THIS COMPLEX...SO MONDAY NIGHT AND TUESDAY COULD BE DRY AS WELL...THUS THE 20-40 PERCENT CHANCES. SIMILAR TO TONIGHT...SHOULD THE COMPLEX ROLL THROUGH...CANNOT RULE OUT SOME SEVERE WEATHER POTENTIAL WITH THEM. COLD FRONTAL PASSAGE OCCURS TUESDAY NIGHT BUT INDICATIONS ARE THAT THE AIRMASS MAY BE TOO CAPPED TO ALLOW ANY CONVECTION WITH IT. IN FACT MOST MODELS ARE DRY. THEREFORE REDUCED CHANCES SUCH THAT ONLY A 20 PERCENT CHANCE IS LEFT CLOSER TOWARDS CENTRAL WI TO BLEND WITH NEIGHBORING OFFICES. WEDNESDAY STILL LOOKS DRY WITH THE FRONT SOUTH OF THE AREA. SMALL CHANCES OF STORMS RETURN THURSDAY THROUGH FRIDAY AS THE FRONT COMES BACK AS A WARM FRONT. DRY CONDITIONS ARE ANTICIPATED SATURDAY WITH THE AREA IN THE WARM SECTOR. ...TEMPERATURE DETAILS... ON MONDAY...EVEN IF THERE ARE STORMS DISSIPATING IN THE MORNING AND NEW ONES FIRE LATER IN THE DAY...ALL INDICATIONS ARE THAT THERE WILL STILL BE PLENTY OF TIME FOR TEMPERATURES TO RECOVER. 925 AND 850MB TEMPS ARE ABOUT 1C HIGHER COMPARED TO TODAY...THUS ANTICIPATING HIGHS 1-2 F HIGHER. UPPER 60S/LOW 70S DEWPOINTS STILL SEEM REASONABLE RESULTING IN 100-105 HEAT INDICES. TUESDAY STILL LOOKS LIKE THE HOTTEST DAY AS 925-850MB WINDS VEER MORE WESTERLY...REALLY ADVECTING THE CORE OF THE HOT AIR OVER SOUTH DAKOTA AND NEBRASKA AT US. 925MB TEMPS CLIMB TO AROUND 30C OVER MOST OF THE FORECAST AREA WHICH IS USUALLY A GOOD CORRELATION FOR 100F TEMPS. RAISED HIGHS A LITTLE MORE AND FURTHER INCREASES MAY BE REQUIRED. DEWPOINTS LOOK LIKE THEY SHOULD HOLD THROUGH EVAPOTRANSPORATION IN THE UPPER 60S/LOW 70S...WHICH MEANS HEAT INDICES COULD CROSS THE 105 WARNING THRESHOLD IN SOME SPOTS. WEDNESDAY IS BECOMING A BIT MORE CONCERNING AS THE 25.00Z ECMWF/GFS ARE NOT AS QUICK BRINGING IN THE COOLER AIR BEHIND THE COLD FRONT. 925MB TEMPS STILL GET UP TO 28C OR HIGHER. THUS...INCREASED HIGHS A FEW DEGREES TO SHOW UPPER 80S TO LOW 90S. THESE MAY NEED TO BE INCREASED MORE...WHICH WOULD PROMPT AN EXTENSION OF THE HEAT ADVISORY ANOTHER DAY. THURSDAY AND FRIDAY WILL BE THE COOLEST DAYS...RELATIVELY SPEAKING AS 925MB TEMPS ONLY COOL TO 25-27C. THEN IF THE NEW 25.00Z ECMWF AND GFS ARE CORRECT...THESE CLIMB RIGHT BACK UP TO EVEN WARMER THAN THE CURRENT HEAT STRETCH...TO 30-32C FOR SATURDAY AND SUNDAY. IF THIS OCCURS...WE COULD EASILY BE LOOKING AT 100 DEGREE HEAT NEXT WEEKEND. && .AVIATION...THROUGH TONIGHT ISSUED AT 650 AM CDT SUN AUG 25 2013 THE LOW LEVEL WIND SHEAR AT KLSE WILL DISSIPATE BY 25.14Z AS DIURNAL MIXING OCCURS AND NOCTURNAL JET WEAKENS. WITH WINDS ALREADY GUSTING INTO THE 25 KNOT RANGE AT KRST...TOOK THE LOW LEVEL WIND SHEER OUT OF THE TAF AT 12Z. FROM 25.14Z THROUGH 26.02Z...THE SOUTHWEST WINDS WILL GUST INTO THE 20 TO 30 KNOT RANGE. FOR LATE TONIGHT...THE MAIN QUESTION IS WHETHER A THUNDERSTORM COMPLEX WILL MOVE SOUTH TO THE INTERSTATE 90 CORRIDOR. BOTH THE NAM AND GFS SUGGEST THAT THIS WILL BE POSSIBILITY. MEANWHILE THE GEM AND ECMWF SUGGEST THAT IT WILL STAY NORTH OF THE AREA. WITH THIS UNCERTAINTY JUST ADDED A VCTS AFTER 26.09Z AT BOTH TAF SITES. IF THESE STORMS DO MOVE INTO THE AREA...THERE WILL BE A POSSIBILITY THAT THEY COULD PRODUCE WIND DAMAGE AND LARGE HAIL. && .CLIMATE... ISSUED AT 330 AM CDT SUN AUG 25 2013 THE FOLLOWING ARE RECORD HIGHS FOR LA CROSSE AND ROCHESTER THROUGH LABOR DAY WEEKEND...GIVEN THE HEAT FORECAST. FOR MORE CLIMATE INFORMATION...SEE OUR WEBSITE AND THE TOP NEWS STORY ON THE HEAT. LA CROSSE ROCHESTER --------- --------- SUN 8/25 97/1948 97/1948 MON 8/26 96/1991 95/1955 TUE 8/27 95/1973 93/1984 WED 8/28 97/1955 96/1955 THU 8/29 95/1966 92/2012 FRI 8/30 97/2012 96/1941 SAT 8/31 95/1953 93/1960 SUN 9/1 98/1913 94/1937 MON 9/2 98/1937 94/1929 NORMAL HIGH TEMPERATURES THROUGH THIS PERIOD ARE 78-80 AT LA CROSSE AND 76-78 AT ROCHESTER. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...HEAT ADVISORY FROM NOON TODAY TO MIDNIGHT CDT TUESDAY NIGHT FOR WIZ017-029-032>034-041>044-053>055-061. MN...HEAT ADVISORY FROM NOON TODAY TO MIDNIGHT CDT TUESDAY NIGHT FOR MNZ079-086>088-094>096. IA...HEAT ADVISORY FROM NOON TODAY TO MIDNIGHT CDT TUESDAY NIGHT FOR IAZ008>011-018-019-029-030. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION...BOYNE CLIMATE...AJ
FORECAST DISCUSSION FOR ROUTINE MORNING FORECAST ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND MONDAY ISSUED AT 500 AM CDT SUN AUG 25 2013 UPPER RIDGE CONTINUES TO FLATTEN OVER THE WESTERN GREAT LAKES AS SHORT WAVE IMPULSE MOVES EAST ACROSS NORTHERN LAKE SUPERIOR THIS MORNING. FOR THE MOST PART...SHORT RANGE MODELS INCLUDING THE HRRR AND RAP DID A RATHER LOUSY JOB HANDLING STRONGER CONVECTION NORTH OF WISCONSIN...AS WELL AS LIGHTER SCATTERED SHOWER ACTIVITY MOVING ACROSS CENTRAL AND NORTHERN WISCONSIN EARLY THIS MORNING. SCATTERED SHOWER AND ISOLATED THUNDERSHOWER ACTIVITY OVER THE FORECAST AREA APPEARS TO BE ASSOCIATED WITH VERY WEAK UPPER-LEVEL IMPULSE...MODEST WAA AND NEAR EASTERN EDGE OF ROBUST CAP EXTENDING FROM CENTRAL MINNESOTA INTO NORTHWEST WISCONSIN. THIS ACTIVITY WILL CONTINUE TO PUSH ACROSS THE FORECAST AREA THIS MORNING AND SHOULD REMAIN SCATTERED AND LIGHT IN INTENSITY. ACTIVITY EXPECTED TO BE EAST OF THE FORECAST AREA BY AROUND 15Z. LOOKING FARTHER UPSTREAM...MORE SCATTERED THUNDERSTORM ACTIVITY HAS DEVELOPED OVER WESTERN MINNESOTA AHEAD OF FRONTAL BOUNDARY OVER THE DAKOTAS. MAJORITY OF THE GUIDANCE SUGGESTS THAT THIS ACTIVITY WILL BEGIN TO SINK MORE SSE ACROSS CENTRAL MINNESOTA LATER THIS MORNING AND GRADUALLY WEAKEN AS IT CONTINUES TO PROPAGATE AWAY FROM FRONTAL BOUNDARY. HOWEVER LATEST RADAR TRENDS SHOWING MORE OF AN EASTWARD MOVEMENT AND IF THIS ACTIVITY HOLDS TOGETHER IT MAY IMPACT THE NORTHWEST PORTION OF THE FORECAST AREA LATE THIS MORNING. WILL NEED TO KEEP AN EYE ON THIS ACTIVITY THIS MORNING. FOR NOW WILL STICK TO CURRENT THINKING THAT THIS ACTIVITY SHOULD WEAKEN BEFORE IT REACHES THE FORECAST AREA. THUS IT APPEARS THAT FORECAST AREA STILL ON TRACK FOR A HOT AND INCREASINGLY HUMID DAY. DID NOT MAKE ANY CHANGES TO PREVIOUS MAX TEMPERATURE FORECAST FOR TODAY THUS STILL EXPECT TEMPS TO REACH THE 90-95 DEGREE RANGE OVER THE WESTERN PORTION OF THE FORECAST AREA WITH READINGS NEAR 90 ACROSS THE NORTHWOODS. DID ADJUST DEWPOINTS DOWN A DEGREE OR TWO THIS AFTERNOON WITH ANTICIPATED AFTERNOON MIXING. THUS HEAT INDICES WILL BE GENERALLY IN 95 TO 100 DEGREE RANGE WITH HIGHEST VALUES OVER THE WESTERN PORTION OF THE FORECAST AREA THIS AFTERNOON. FOR THIS EVENING AND TONIGHT...QUESTION THEN BECOMES WHEN AND WHERE THUNDERSTORM ACTIVITY WILL FIRE AS SHORTWAVE IMPULSE HEADS EAST TOWARD THE WESTERN GREAT LAKES AND FRONTAL BOUNDARY APPROACHES. ALTHOUGH THERE HAS BEEN A VARIETY OF SOLUTIONS AS TO HOW THE SCENARIO WILL PLAY OUT...SEEMS THAT A WEAK CONSENSUS OF THE GUIDANCE SUGGESTS THAT THUNDERSTORM ACTIVITY WILL DEVELOP NEAR THE WISCONSIN-MICHIGAN BORDER...ALONG AND AHEAD OF FRONTAL BOUNDARY FORECAST TO DRIFT SSE INTO NORTHERN WISCONSIN THIS EVENING. THIS BOUNDARY MAY ALSO GET SOME REINFORCEMENT FROM LAKE SUPERIOR BREEZE. THIS ACTIVITY SHOULD THEN SAG SOUTHWARD ACROSS THE FORECAST AREA OVERNIGHT INTO MONDAY MORNING. SHOULD BE PLENTY OF INSTABILITY OVER THE FORECAST AREA SUNDAY EVENING WITH MLCAPES AROUND 3000 J/KG. BEST DEEP LAYER SHEAR TO SUSTAIN UPDRAFTS WILL BE OVER THE NORTHERN HALF OF THE FORECAST AREA. SPC ADDED MOST OF THE FORECAST AREA INTO A SLIGHT RISK FOR SEVERE LATE THIS AFTERNOON AND INTO THE LATE EVENING HOURS WHICH SEEMS REASONABLE. PRIMARY THREAT APPEARS TO BE DAMAGING WINDS AND PERHAPS SOME LARGE HAIL. MODELS VARY AS TO THE TIMING THE CONVECTION WILL FIRE...BEST GUESS IS SOMETIME IN THE 23-02Z TIME FRAME WITH ACTIVITY MOVING SOUTH OR SOUTHEAST ACROSS THE FORECAST AREA TOWARD MIDNIGHT. WILL ALSO NEED TO KEEP AN EYE ON A LOCALLY HEAVY RAINFALL THREAT...ESPECIALLY IF ACTIVITY CAN TRAIN FROM WEST TO EAST ALONG FRONTAL BOUNDARY LATER TONIGHT. MORE UNCERTAINTY FOR MONDAY AS MODELS DIVERGE ON HOW LONG ACTIVITY WILL PERSIST ALONG FRONTAL BOUNDARY EXPECTED TO BE LOCATED SOMEWHERE OVER NORTHERN WISCONSIN. LOCATION OF RESIDUAL THUNDERSTORM OUTFLOW IS ALSO A FACTOR AS TO WHERE ADDITIONAL CONVECTION MAY FIRE AGAIN DURING THE DAY ON MONDAY. FOR NOW KEPT BROAD BRUSH CHANCE POPS ACROSS THE ENTIRE FORECAST AREA. MAX TEMPS ON MONDAY WILL BE DEPENDENT ON RESIDUAL CLOUD COVER...PRECIPITATION AND LOCATION OF FRONTAL BOUNDARY. .LONG TERM...MONDAY NIGHT THROUGH SATURDAY ISSUED AT 501 AM CDT SUN AUG 25 2013 WHILE THE CNTRL CONUS UPR RDG TO REMAIN THE MAIN WEATHER FEATURE THRU MUCH OF THE UPCOMING WEEK...ITS SLOW RETROGRESSION FROM THE MID-MS VALLEY TO THE CNTRL HI PLAINS WL ALLOW THE MEAN FLOW TO TURN NW BY THU AND BRING SLIGHTLY COOLER/DRIER CONDITIONS TO NE WI. MAIN FCST EMPHASIS TO BE THRU MID-WEEK AS A FRONTAL BOUNDARY MOVES THRU AN UNSTABLE AIR MASS AND SETS THE STAGE FOR TSTMS. A FEW OF THESE STORMS MAY BECOME STRONG TO SEVERE WITH LOCALLY HEAVY RAINFALL. TEMPS TO REMAIN WELL ABOVE NORMAL TIL FURTHER NOTICE... ESPECIALLY THRU THU. PLENTY OF QUESTIONS LINGER FOR TUE STARTING WITH WHERE (IF) MON NGT`S CONVECTION TO BE LOCATED...WHERE THE NRN WI FRONTAL BOUNDARY TO RESIDE...WL ADDITIONAL PCPN DEVELOP ON THE EDGE OF THE CAP AND COULD ANY OF THESE STORMS TURN SEVERE? THE KEY APPEARS TO BE THE MON NGT CONVECTION SINCE IF IT WERE TO DEVELOP...MORE CLOUDS AND BRIEF STABILIZATION WOULD OCCUR. IF THIS CONVECTION STAYS TO THE NORTH...THIS WOULD ALLOW TEMPS TO SOAR ONCE AGAIN AND ALLOW THE ATMOSPHERE TO REALLY DESTABILIZE BY THE AFTERNOON. TO TOP ALL OF THIS OFF...THE MDLS BRING A WEAK SFC TROF INTO WI. HARD TO FATHOM NOT SEEING ANY PCPN MON NGT...THUS HAVE SIDED WITH MENTIONING A HIGHER POP ON TUE ACROSS FAR NE WI WHERE THE WEAKER CAP WL EXIST. SEVERE POTENTIAL TO BE DICTATED BY HOW WARM WE CAN GET AND WHETHER THAT APPROACHING WEAK SFC TROF CAN GENERATE ENUF LIFT TO BREAK THE CAP. IF THE CAP IS BROKEN...WE COULD SEE A ROUND OF STRONG TO SEVERE STORMS WITH LARGE HAIL...DAMAGING WINDS AND TORRENTIAL DOWNPOURS. SHWR/TSTM THREAT WOULD CARRYOVER INTO TUE EVENING UNTIL THE SFC TROF EXITS THE AREA AND A WEAK AREA OF HI PRES BEGINS TO BUILD ACROSS THE UPR MS VALLEY. ONLY CHANGE TO THIS PART OF THE FCST WAS TO FOCUS PCPN CHCS TO THE EVENING WITH A CLEARING TREND FOR THE OVRNGT HOURS. BY THE MIDDLE OF THE WEEK...THE UPR RDG IS PROGGED TO HAVE RETROGRADED BACK TOWARD THE CNTRL PLAINS WTH THE MEAN FLOW OVER THE GREAT LAKES TURNING MORE NW. WEAK HI PRES TO BE SITUATED OVER THE WRN GREAT LAKES REGION ON WED...THUS A DECENT AMOUNT OF SUNSHINE IS ANTICIPATED. 8H TEMPS TO STILL BE AROUND +20C...SO TEMPS WL REMAIN RATHER WARM WITH A MINOR DROP IN DEW POINTS BEHIND THE DEPARTED SFC TROF. THERE ARE NOW CONCERNS FOR THU`S DRY FCST AS THE MDLS ARE INDICATING THE NEXT MID-LEVEL SHORTWAVE TROF TO BE ROUNDING THE CNTRL CONUS UPR RDG AND DIVING SE TOWARD WI. NOT SURE AT THIS POINT WHETHER THIS POTENTIAL CONVECTION WOULD IMPACT ALL OF NE WI OR DIVE SE ENUF TO ONLY AFFECT CNTRL WI. AT THIS POINT...FOLLOWED THE CONSENSUS SOLUTION WHICH BRINGS A SLIGHT CHC POP TO MUCH OF THE FCST AREA. TEMPS FOR WED LOOK TO BE SIMILAR TO WED WITH PLENTY OF 80S TO GO AROUND. ANOTHER AREA OF HI PRES IS EXPECTED TO BUILD SWD FROM CANADA DURING THE THU NGT/FRI TIME PERIOD. DO NOT CARE FOR THE MINIMAL POP ADVERTISED BY THE CONSENSUS SOLUTION AND PREFER TO GO DRY FOR FRI WITH TEMPS GENERALLY IN THE 80-85 DEG RANGE. RETURN FLOW THEN SETS UP OVER THE REGION NEXT WEEKEND WHICH WL LEAD TO WARMER TEMPS...AN UPTICK IN HUMIDITY LEVELS AND THE POSSIBILITY OF WAA- INDUCED PCPN CHCS. ATTM...ANY PCPN APPEARS TO BE WIDELY SCT AT BEST WITH NO FOCUSING MECHANISM PRESENT. && .AVIATION...FOR 12Z TAF ISSUANCE ISSUED AT 501 AM CDT SUN AUG 25 2013 GENERALLY VFR CONDITIONS TODAY. SCATTERED THUNDERSTORM ACTIVITY WILL BEGIN TO SPREAD FROM NORTHWEST TO SOUTHEAST ACROSS THE FORECAST AREA TONIGHT...HOWEVER CONFIDENCE LOW AS TO WHEN CONVECTION WILL FIRE THIS EVENING AND HOW FAR SOUTH IT WILL PROPAGATE OVERNIGHT. BEST CHANCE FOR MVFR CONDITIONS ASSOCIATED WITH SCATTERED THUNDERSTORM ACTIVITY WILL BE AT NORTHERN TAF SITES AFTER 03Z. . && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....ESB LONG TERM......KALLAS AVIATION.......ESB
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
340 PM EDT SUN AUG 25 2013 .SYNOPSIS...19Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS MUCH OF THE CENTRAL AND EASTERN PORTIONS OF THE CONUS UNDER THE DOMAIN OF A LARGE AND AMPLIFIED UPPER LEVEL RIDGE. THIS RIDGE CENTER/AXIS EXIST NEAR AND JUST TO THE WEST OF THE MIDDLE MS VALLEY. FURTHER DOWNSTREAM... LONGWAVE TROUGHING HAS EXITED THE EASTERN SEABOARD WITH A WEAK EXTENSION OF THE TROUGH AXIS BACK TO THE SOUTHWEST TOWARD THE FLORIDA PENINSULA. WV IMAGERY STILL SHOWS PLENTY OF MID/HIGH LEVEL MOISTURE IN PLACE OVER THE PENINSULA...BUT AN AREA OF MUCH DRIER AIR ALOFT AND DECENT SYNOPTIC SUPPRESSION CAN BE SEEN OVER THE CAROLINAS/GEORGIA. THIS SYNOPTIC SETUP IS CURRENTLY MAKING A VERY SLOW PUSH INTO NORTHERN FLORIDA...BUT GLOBAL GUIDANCE AGREES ON A MORE SIGNIFICANT PUSH SOUTHWARD DOWN THE PENINSULA OCCURRING LATER TONIGHT AND MONDAY MORNING. THIS ACTION WILL SCOUR OUT THE DEEPER MOISTURE AND ALONG WITH INCREASING ANTI-CYCLONIC FLOW ALOFT/DEEP LAYER SUPPRESSION WILL HELP TO BRING OUR RAIN CHANCES BACK DOWN TO CLIMO NORMS...OR LESS...FOR THE EARLY PORTION OF THE UPCOMING WORK WEEK. AT THE SURFACE...STRONG RIDGE OF HIGH PRESSURE IS CENTERED OVER THE MID-ATLANTIC/CAROLINAS AND WILL PROVIDE A NE TO EAST LOW LEVEL FLOW THROUGH THE PERIOD AS IT SLOWLY SINKS SOUTH AND BEGINS TO WEAKEN. && .SHORT TERM (TONIGHT THROUGH TUESDAY)... LEFTOVER MID/LATE EVENING STORMS WILL SHIFT/RE-DEVELOP OFFSHORE AFTER MIDNIGHT LEAVING THE LAND ZONES GENERALLY DRY AFTER 02-03Z. THE LESS FAVORABLE CONDITIONS (FOR DEEP CONVECTION) PUSHING SOUTH MAY KEEP THE BEST OFFSHORE STORM COVERAGE TO THE SOUTH OF TAMPA BAY LATE TONIGHT INTO MONDAY MORNING...AND THIS CONTINUES TO BE A THEME IN MANY OF THE LARGER SCALE PARAMETRIZED 12Z GUIDANCE. MONDAY/MONDAY NIGHT... DEEPER MOISTURE IS SHOWN TO EXIT SOUTH OF LEE/CHARLOTTE COUNTIES BY EARLY AFTERNOON ALONG WITH THE LINGERING SYNOPTIC SUPPORT FROM THE UPPER TROUGH. GFS IS ACTUALLY SHOWING SOME RATHER IMPRESSIVE DEEP LAYER Q-VECTOR DIVERGENCE OVER THE REGION TOMORROW...WHICH WILL WORK AGAINST ANOTHER ABNORMALLY WET AFTERNOON/EVENING. GIVEN THE FORECAST ATMOSPHERIC COLUMN...A MORE CLIMO CHANCE POP (40-50%) STORM COVERAGE CAN BE EXPECTED SOUTH OF I-4. WAS ORIGINALLY THINKING ONLY ISOLATED / SLIGHT CHANCE POPS FOR THE NATURE COAST...HOWEVER LATEST GUIDANCE HAS A BIT MORE ATLANTIC MOISTURE IN THE LOWER TROP GETTING INTO THE MIX FOR THESE NORTHERN ZONES. THEREFORE WILL KEEP POPS IN THE CHANCE RANGE 30-40% FOR THE NATURE COAST...HOWEVER SHOWERS OVER THESE NORTHERN COUNTIES ARE LIKELY TO BE MORE SHALLOW AND BRIEF IN NATURE / LIFE CYCLE DUE TO THE DRIER AIR ALOFT. THIS SHOULD LIMIT THE RAINFALL QPF POTENTIAL...WHICH IS GOOD NEWS FOR AREAS THAT NEED SOME TIME TO DRY OUT FROM THE SIGNIFICANT RAINFALL OF THE PAST SEVERAL DAYS. EVEN THE LOWER LEVEL ATLANTIC MOISTURE LOOKS NOW TO BE SCOURED OUT MONDAY NIGHT WHICH SHOULD LEAD TO A DRY OVERNIGHT PERIOD AFTER ANY ISOLATED MID EVENING SHOWERS PUSH OFFSHORE / DIMINISH. THE DRIER COLUMN AND CLEARING SKIES MAY ALSO ALLOW FOR SOME "COOLER" OVERNIGHT LOWS BY DAWN. WOULD NOT BE SURPRISED TO SEE PORTIONS OF THE NATURE COAST AND INLAND SOUTH-CENTRAL ZONES REACH THE UPPER 60S. BREAK OUT THE COATS! TUESDAY... THE DRIER COLUMN IS WELL ENTRENCHED FOR THE AFTERNOON. DURING THE FORECAST PROCESS YESTERDAY...WAS CONCERNED WITH THE INFLUENCE OF AN UPPER LOW THAT THE GFS WAS TRYING TO CLOSE OFF NEAR THE SW FLORIDA COAST. LAST COUPLE OF GFS RUNS HAVE COME AROUND MORE TO THE ECMWF SOLUTION...WHICH IS LATER AND LOCATED CLOSER TO THE BAHAMAS. THIS TREND SUGGESTS THAT THIS FEATURE WILL HAVE LITTLE INFLUENCE ON OUR LOCAL WEATHER THROUGH THE SHORT TERM PERIOD (IF EVER). WILL STILL HAVE LIGHT EASTERLY FLOW ON TUESDAY WHICH GENERALLY IS FAVORABLE FOR CONVECTION ALONG THE FL WEST COAST. HOWEVER...GIVEN THE DRY COLUMN ALOFT AND GENERAL ANTI-CYCLONIC NATURE OF THE FLOW ALOFT...WILL KEEP THE TYPICAL SPATIAL POP PATTERN FOR CONVECTION IN EASTERLY FLOW...BUT DROP THE RAIN CHANCES DOWN CLOSER TO THE ECMWF MOS GUIDANCE NUMBERS. DESPITE THE DRIER AIR...THE GFS MOS NUMBERS SEEM TOO LOW FOR EASTERLY FLOW AND WILL DISREGARD FOR NOW. AFTERNOON/EVENING RAIN CHANCES WILL FEATURE 30-40% SOUTH OF TAMPA BAY...AND 20-30% FOR THE I-4 CORRIDOR NORTHWARD ALONG THE NATURE COAST...WHERE THE PROXIMITY TO THE UPPER RIDGE WILL PROVIDE THE GREATEST DEGREE OF SYNOPTIC SUPPRESSION. && .LONG TERM (WEDNESDAY-SUNDAY)... MEDIUM RANGE GUIDANCE IS IN GOOD AGREEMENT SHOWING THE HIGH PRESSURE RIDGE AXIS ACROSS NORTH FLORIDA TO START THE DAY WEDNESDAY...WITH THE AXIS SHIFTING STEADILY SOUTHWARD INTO SOUTH FLORIDA BY FRIDAY EVENING. THE RIDGE AXIS WILL REMAIN ACROSS SOUTH FLORIDA AND THE FLORIDA STRAIGHTS OVER THE UPCOMING WEEKEND AS A TROUGH OF LOW PRESSURE STALLS OUT ALONG THE NORTHERN GULF COAST. OVERALL...EXPECT ISOLATED/SCATTERED MAINLY AFTERNOON/EVENING SHOWERS AND THUNDERSTORMS WEDNESDAY THROUGH FRIDAY. SHOULD SEE AN INCREASE IN SHOWER/THUNDERSTORM COVERAGE OVER THE UPCOMING WEEKEND AS DEEPER MOISTURE ASSOCIATED WITH THE TROUGH OF LOW PRESSURE PUSHES SOUTHWARD INTO THE AREA. TEMPERATURES ARE EXPECTED TO RUN CLOSE TO CLIMO THROUGH THE LONG TERM PERIODS. && .AVIATION... BKN MID/HIGH CLOUDS THROUGH THE EVENING...WITH VCNTY TSRA UNTIL 02Z. BETWEEN 21Z-00Z TEMPO MVFR VSBY/CIG IN TSRA WITH LCL IFR PSBL. HIGH PRESSURE BUILDING IN TO THE NORTH WILL PROVIDE AN E-NE FLOW...KEEPING THE SEA BREEZE CLOSE TO THE COAST THIS AFTERNOON...THROUGH MON. && .MARINE... A STRONG RIDGE OF HIGH PRESSURE CURRENTLY CENTERED NEAR THE MID-ATLANTIC STATES WILL SLOWLY WEAKEN AS IT SETTLES SOUTHWARD TOWARD THE EASTERN GULF OF MEXICO DURING THE NEXT SEVERAL DAYS. THE POSITION OF THIS RIDGE WILL BE FAVORABLE THE NEXT COUPLE OF NIGHTS FOR ENHANCED EASTERLY FLOW THAT WILL LINGER INTO THE EARLY MORNING HOURS. WINDS WILL BE STRONGEST AND POTENTIALLY APPROACH CAUTIONARY LEVELS AT TIMES TO THE NORTH OF TARPON SPRINGS. BY MIDWEEK THE RIDGE WILL APPROACH THE AREA ALLOW THE GRADIENT AND RESULTING WINDS TO DIMINISH WELL BELOW HEADLINE CRITERIA. && .FIRE WEATHER... HIGH PRESSURE WELL TO OUR NORTH WILL SLOWLY SLIDE SOUTHWARD THROUGH THE EARLY PORTION OF THE WEEK. DRIER AIR ALOFT WILL RESULT IN A MORE TYPICAL DISTRIBUTION OF AFTERNOON AND EVENING STORMS THE NEXT SEVERAL DAYS COMPARED TO THE WIDESPREAD ACTIVITY SEEN IN PAST DAYS. DESPITE THE DRIER AIR ALOFT...NO SIGNIFICANT PUSH OF DRIER AIR IN THE LOWER LEVELS IS EXPECTED AND RELATIVE HUMIDITY VALUES ARE FORECAST TO REMAIN WELL ABOVE CRITICAL LEVELS. AT THIS TIME...NO SIGNIFICANT FIRE WEATHER CONCERNS ARE ANTICIPATED THROUGH THE MIDDLE OF THE WEEK. && .HYDROLOGY... THE CYPRESS CREEK AT WORTHINGTON GARDENS IS THE ONLY RIVER CURRENTLY EXPECTED TO REACH FLOOD STAGE. AS OF 3PM...WATER LEVEL IS AT 7.4 FEET WITH FLOOD STAGE REACHED AT 8 FEET. THE RIVER IS EXPECTED TO REACH FLOOD STAGE LATE IN THE DAY ON MONDAY OR EARLY TUESDAY. WATER LEVELS ON THE HORSE CREEK NEAR ARCADIA REMAIN HIGH...BUT THE RIVER IS EXPECTED TO STAY JUST BELOW FLOOD STAGE OVER THE NEXT FEW DAYS. HOWEVER ANY HEAVY PERSISTENT RAINFALL FROM AFTERNOON SHOWERS AND THUNDERSTORMS OVER THESE BASINS COULD CAUSE WATER LEVELS TO RISE MORE THAN CURRENTLY FORECAST. && .PRELIMINARY POINT TEMPS/POPS... TPA 74 90 75 91 / 30 40 20 30 FMY 74 90 73 91 / 30 50 30 40 GIF 72 91 72 92 / 20 40 20 30 SRQ 74 90 74 91 / 30 40 30 30 BKV 71 90 70 91 / 20 40 20 30 SPG 77 90 78 90 / 30 40 30 30 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...NONE. GULF WATERS...NONE. && $$ SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA LONG TERM...JELSEMA AVIATION...RUDE HYDROLOGY...MCKAUGHAN
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1121 AM MDT SUN AUG 25 2013 .UPDATE... ISSUED AT 912 AM MDT SUN AUG 25 2013 DECREASED WINDS A FEW KNOTS FOR THIS AFTERNOON BASED ON WINDS MIXING DOWN FROM 700MB WHERE THE TOP OF THE MIXED LAYER WILL BE. SO FAR THE DAY LOOKS VERY SIMILAR TO YESTERDAY. AM A BIT CONCERNED WITH THE MORE SOUTH-SOUTHWEST DIRECTION OF THE WINDS AS THIS MAY ALLOW DEW POINTS TO FALL A FEW MORE DEGREES THAN YESTERDAY. SO FAR LOOKS LIKE WINDS/RELATIVE HUMIDITIES WILL BE VERY CLOSE TO MEETING CRITICAL FIRE WEATHER CONDITIONS. AT THIS TIME...AND BASED ON WHAT HAPPENED YESTERDAY...DO NOT HAVE ENOUGH CONFIDENCE TO ISSUE ANY FIRE WEATHER PRODUCTS FOR THE AFTERNOON. THE RECENT RAINS ALSO ADD MORE COMPLEXITY TO WHERE THE FUELS WILL BE FAVORABLE FOR RAPID FIRE GROWTH AND WHERE THEY WONT BE. AT THIS POINT CHEYENNE TO RAWLINS AND SHERMAN TO THOMAS COUNTIES AND RED WILLOW COUNTY LOOK TO BE THE MOST FAVORABLE FOR CRITICAL FIRE WEATHER CONDITIONS. WILL CONTINUE TO MONITOR IN CASE A FIRE WEATHER PRODUCT IS NEEDED. && .SHORT TERM...(TODAY THROUGH TUESDAY NIGHT) ISSUED AT 254 AM MDT SUN AUG 25 2013 LITTLE IS GOING TO CHANGE REGARDING THE THE LARGE SCALE PATTERN ACROSS THE CENTRAL US...WITH HOT/DRY CONDITIONS EXPECTED OVER OUR CWA. LARGE H5 RIDGE REMAIN IN PLACE OVER THE CENTRAL CONUS...WITH LATEST RAP ANALYSIS SHOWS 595DM CENTER ACROSS KS/MO STATE LINE. GFS/NAM SHOW HEIGHTS CONTINUING TO RISE THROUGH THE DAY WITH 597-598DM CENTER BY 00Z THIS AFTERNOON. WITH DRY/STABLE AIR MASS IN PLACE PRIMARY CONCERN WILL CONTINUE TO BE HOT TEMPERATURES AND MARGINAL FIRE WEATHER CONDITIONS IN THE WEST. STRONG LEE TROUGH WILL REMAIN IN PLACE THROUGH MONDAY...WITH STRONG SOUTHERLY PRESSURE GRADIENT OVER OUR CWA. BREEZY TO WINDY CONDITIONS ARE EXPECTED TODAY THROUGH MONDAY...WITH LATEST GUIDANCE BEGINNING TO SHOW WINDY CONDITIONS FURTHER WEST WHERE LOWER RH VALUES WILL BE. AT THIS POINT...IT APPEARS WE WILL BE JUST OUTSIDE OF RFW CRITERIA FOR RH...THOUGH I COULDNT RULE OUT A FEW WESTERN LOCATIONS FALLING JUST WITHIN LOCAL CRITERIA. I AM NOT PLANNING ON ISSUING A WARNING AT THIS TIME DUE TO THE MARGINAL AND ISOLATED NATURE OF THESE CONDITIONS. THERE IS ALSO A QUESTION REGARDING FUELS...WITH ISOLATED PARTS OF OUR CWA HAVING RECEIVED QUITE A BIT OF RAINFALL SINCE LATE JUNE DESPITE THE MAJORITY OF THE AREA REMAINING IN DROUGHT. SATELLITE DERIVED GREENNESS PRODUCTS SHOW PREDOMINANTLY GREEN FUELS OVER PARTS OF THE TRI-STATE AREA...THOUGH THERE ARE PARTS OF MANY COUNTIES THAT FALL BELOW NORMAL GREENNESS LEVELS. IF CONDITIONS WERE LESS MARGINAL...THE STATUS OF FUELS MIGHT STILL PREEMPT ISSUANCE OF RFW FOR PARTS OF OUR CWA. REGARDING HIGH/LOW TEMPS...I USED BIASES FROM SUN AS THE BASIS FOR THE FORECAST THROUGH TUE WITH VERY SIMILAR AIR MASS IN PLACE EACH DAY. I ALSO TRENDED LOW TEMPS UP FROM PREVIOUS FORECAST WITH BREEZY WINDS LIKELY IMPACTING RADIATIONAL COOLING EACH NIGHT. FORECAST IS STILL CALLING FOR UPPER 90S/LOW 100S EACH AFTERNOON..AND BY MON/TUE I WOULDNT BE SURPRISED IF WE SAW A FEW LOCATIONS COME WITHIN A FEW DEGREES OF RECORD HIGHS. .LONG TERM...(WEDNESDAY THROUGH SATURDAY) ISSUED AT 254 AM MDT SUN AUG 25 2013 MUCH OF THE SAME FOR THE SECOND HALF OF THIS WEEK WITH HOT AND DRY CONDITIONS CONTINUING. A BROAD H5 RIDGE CENTERED OVER KANSAS WILL BE WELL-ESTABLISHED BY MID-WEEK. THIS RIDGE WILL GRADUALLY BUILD WEST OVER THE REST OF THE WEEK...KEEPING THE SENSIBLE WX FAIRLY BENIGN. THE ONLY INTERESTING FEATURE IS A WEAK VORT MAX THAT MAY MOVE ACROSS EASTERN COLORADO INTO WESTERN KANSAS LATE THURSDAY. WHILE THERE WILL BE SOME UPPER-LEVEL MOISTURE...SOUNDINGS APPEAR TOO STABLE TO SUPPORT WIDESPREAD STORMS. THE OPERATIONAL GFS PRINTS OUT SOME QPF IN WESTERN KANSAS FROM THIS...AS WELL AS JUST ONE OF THE TWELVE ENSEMBLE PERTURBATIONS...SO HAVE LITTLE CONFIDENCE IN ANY PRECIP BEING REALIZED. RIDGE CONTINUES DRIFTING WESTWARD OVER THE WEEKEND WHILE AN UPPER LOW MOVING INTO THE PACIFIC NORTHWEST MAY HELP TO WEAKEN THE RIDGE LATE IN THE WEEKEND. FOR NOW...NO PRECIP CHANCES THROUGH SATURDAY AFTERNOON. FOR TEMPS...ALL GUIDANCE CONTINUES TO TREND WARMER FOR THE PERIOD WITH 850MB TEMPS IN THE LOW 30S C. TEMPS WILL BE NEARLY THE SAME EVERY DAY...HIGHS IN THE MID TO UPPER 90S AND LOWS IN THE MID 60S TO LOW 70S. HIGHS ARE NOT EXPECTED TO BE RECORD BREAKING...BUT A FEW STATIONS COULD APPROACH RECORD HIGHS ANY DAY OF THE EXTENDED. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 1120 AM MDT SUN AUG 25 2013 VFR CONDITIONS FORECAST FOR THE 18Z TAFS. VERY SIMILAR CONDITIONS IN PLAY TODAY COMPARED TO YESTERDAY. SOUTHERLY WINDS WILL REMAIN GUSTY THROUGH THE AFTERNOON AND WELL INTO THE EVENING THEN RETURN MID TO LATE MORNING MONDAY. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...JTL SHORT TERM...DR LONG TERM...JJM AVIATION...JTL
AREA FORECAST DISCUSSION
NWS GRAY ME
428 PM EDT SUN AUG 25 2013 .SYNOPSIS... A WARM FRONT WILL APPROACH FROM THE NORTHWEST TONIGHT AND WILL GRADUALLY CROSS THE REGION ON MONDAY FOLLOWED BY A WEAK COLD FRONT MONDAY NIGHT. WEAK HIGH PRESSURE WILL BUILD OVER THE AREA ON TUESDAY. LOW PRESSURE WILL APPROACH FROM THE WEST TUESDAY NIGHT AND WILL PASS SOUTH OF NEW ENGLAND ON WEDNESDAY. A TROUGH OF LOW PRESSURE WILL LINGER OVER THE REGION ON THURSDAY AS LOW PRESSURE SHIFTS EAST INTO THE MARITIMES. THE TROUGH WILL SLOWLY MOVE SOUTH THROUGH THE REGION ON FRIDAY. HIGH PRESSURE WILL BUILD IN FROM THE NORTHWEST ON SATURDAY. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... UPDATE... HAVE UPDATED GRIDS BASED ON CURRENT DEW POINT AND TEMPERATURES OBSERVATIONS. CLOUDS WILL ALSO BE ENTERING THE FORECAST AREA SHORTLY FROM THE WEST...WITH THE LATEST HRRR RUN TIMING ANY SHOWER ACTIVITY WILL OCCUR AFTER MIDNIGHT OVER WESTERN ZONES. PREV DISC... INCREASING CLOUDS TONIGHT AS A WARM FRONT APPROACHES FROM THE WEST. CONVECTIVE COMPLEX MOVING THROUGH EASTERN ONTARIO WILL DIE OUT OVER WESTERN NEW YORK LATER THIS AFTERNOON AND THIS EVENING BUT A FEW SHOWERS WILL EVENTUALLY MAKE IT INTO THE FORECAST AREA GENERALLY AFTER MIDNIGHT. SHOULD SEE A MUCH WARMER NIGHT WITH LOWS RANGING THROUGH THE 50S FROM NORTH TO SOUTH. && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... ANY LINGERING SHOWERS WILL PUSH SOUTH OF THE REGION MONDAY MORNING AND MUCH OF THE DAY NOW LOOKS DRY WITH VARIABLE MID LEVEL CLOUDS. MAY BE ENOUGH INSTABILITY IN SOUTHERN NEW HAMPSHIRE TO POP OFF AN AFTERNOON SHOWER OR THUNDERSTORM BUT APPEARS BEST CAPES REMAIN SOUTH AND WEST OF THE FORECAST AREA. EXPECT HIGH FROM THE MID 70S TO NEAR 80. WEAK COLD FRONT WILL DROP SOUTH THROUGH THE REGION MONDAY NIGHT. MAY BE ENOUGH TO POP OFF AN ISOLATED SHOWER OR THUNDERSTORM BUT NOT LOOKING FOR ANY WIDESPREAD ACTIVITY. WILL BE ANOTHER MILD NIGHT WITH LOWS IN THE MID 50S TO LOWER 60S. && .LONG TERM /TUESDAY THROUGH SUNDAY/... THE UPPER LEVEL TROF AND WEAK LOW/SFC WARM FRONT MOVE TO OUR E AND SE BY 12Z TUESDAY ALLOWING WEAK HIGH PRESSURE UNDER AN UPPER LEVEL RIDGE TO BUILD INTO THE REGION GIVING US FAIR AND VERY WARM WX FOR TUESDAY INTO EARLY TUESDAY NIGHT. A BROAD LARGE SCALE UPPER LEVEL RIDGE BUILDS OVER THE CENTRAL AND WRN U.S. ALLOWING A LONG WAVE TROF TO CARVE OUT OVER THE ERN U.S. AS A SERIES OF WEAK UPPER LEVEL TROFS MOVE INTO THE ERN U.S. THIS WILL PROVIDE UNSETTLED WX FROM LATE TUESDAY NIGHT THRU WEDNESDAY EVENING UNTIL A MORE ORGANIZED UPPER LEVEL TROF FORMS AND FORCES LOW PRESSURE TO GAIN SOME STRENGTH WHILE MOVING FROM S OF THE GULF OF MAINE OFF TO THE NE ON THURSDAY. DEPENDING ON HOW CLOSE THE SFC LOW TRACKS WILL DETERMINE IF WE RECEIVE MORE ORGANIZED RAIN LATE WEDNESDAY NIGHT THROUGH THURSDAY MORNING AND POSSIBLY INTO THE AFTERNOON. THE AXIS OF THE UPPER LEVEL TROF SHIFTS SLOWLY EAST BUT MAINTAINS A CYCLONIC FLOW ALOFT THURSDAY NIGHT AND FRIDAY SO THAT SOME INSTABILITY SHRA ARE POSSIBLE. GRADUALLY AN UPPER LEVEL RIDGE BUILDS IN FRIDAY NIGHT AND SATURDAY ALLOWING HIGH PRESSURE TO APPROACH FROM CANADA. THIS BRINGS DRIER AND COOLER WX FRIDAY NIGHT AND SATURDAY. THE UPPER LEVEL RIDGE BREAKS DOWN AS A SHORT WAVE DRIVES EASTWARD THRU THE RIDGE BRINGING WARMER AND MORE HUMID AIR /THUS INCREASING INSTABILITY/ INTO THE REGION ALONG WITH ISOLD TO MAYBE SCT SHRA AND TSTMS ON SUNDAY...EVEN THOUGH THE TROF IS WEAKENED AS IT MOVES THRU THE UPPER LEVEL RIDGE AND THE ASSOCIATED WEAK SFC FRONT STAYS WELL TO OUR NW. GENERALLY USED BLEND OF GFS/NAM/MET/MAV/HPC QPF FOR PERIODS 4 AND 5 THEN A BLEND OF GFS40/GMOS/MEX FOR THE REST OF THE LONG TERM FCST. && .AVIATION /21Z SUNDAY THROUGH FRIDAY/... SHORT TERM...VFR TONIGHT THROUGH MONDAY. AREAS OF MVFR/IFR CEILINGS MONDAY NIGHT. LONG TERM /TUESDAY THROUGH FRIDAY/...UNSETTLE WX LATE TUESDAY NIGHT THRU THURSDAY AND POSSIBLY INTO FRIDAY WITH THE POTENTIAL FOR MVFR/IFR CONDITIONS AT TIMES. && .MARINE... SHORT TERM...NO FLAGS. LONG TERM /TUESDAY THROUGH FRIDAY/...WINDS AND SEAS EXPECTED TO BE BELOW SCA CRITERIA DUE TO WEAK PRESSURE GRADIENT. HOWEVER... PASSING LOW OUTSIDE OF THE COASTAL WATERS MAY STRENGTHEN ON THURSDAY AND THURSDAY NIGHT THAT COULD PRODUCE CONDITIONS APPROACHING SCA LEVELS. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...NONE. && $$
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
351 PM EDT SUN AUG 25 2013 LATEST UPDATE... SYNOPSIS/SHORT TERM/LONG TERM/HYDRO/MARINE .SYNOPSIS... ISSUED AT 350 PM EDT SUN AUG 25 2013 A WARM FRONT WILL MOVE EAST OF THE AREA THIS EVENING PUTTING SOUTHWEST MICHIGAN IN WARM AND HUMID AIR UNTIL THE COLD FRONT COMES THROUGH WEDNESDAY MORNING. EXPECT PERIODS OF THUNDERSTORMS FROM MONDAY AFTERNOON INTO WEDNESDAY MORNING. FOR MOST OF THE AREA THE GREATEST RISK OF SIGNIFICANT RAINFALL IS TUESDAY INTO TUESDAY NIGHT. WARM DRY WEATHER WILL THEN PREVAIL UNTIL THE NEXT WARM FRONT COMES THROUGH NEXT WEEKEND. THAT COULD BE THE HOTTEST WEATHER OF THE SUMMER. && .SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT) ISSUED AT 350 PM EDT SUN AUG 25 2013 WE ARE WATCHING TWO SIGNIFICANT FEATURES THIS AFTERNOON... FIRST IS THE POTENTIAL FOR THUNDERSTORMS ONCE WE ARE SOLIDLY IN THE WARM AND HUMID AIR... THEN THE SECOND ISSUE IS JUST HOW HOT IT GET THE NEXT TWO AFTERNOONS. FIRST THE CONVECTION ISSUE. IT NOW SEEMS THE FRONTAL BOUNDARY OVER THE UPPER PENINSULA WILL NOT MAKE MUCH PROGRESS SOUTH TONIGHT SO I DO NOT EXPECT THE CONVECTION ASSOCIATED WITH IT TO MAKE MUCH PROGRESS EITHER. THIS IS SHOWN BY THE NSSL AND SPC WAF... AND THE HRRR MODELS AS WELL AS THE RAP MODEL. WELL THE CONVECTION WILL MOVE SOUTH FROM WHERE IT IS BUT IT SHOULD NOT GET MUCH FATHER SOUTH THEN ROUTE 10 BY MORNING SO I HAVE LOW CHANCE POPS UP THERE. THAT IS BASED ON THE LOW LEVEL JET AXIS NOT GETTING MUCH FARTHER SOUTH THAN CAD/HTL BY 12Z. NOTE THAT THERE ARE TWO PRIMARY SHORTWAVES DRIVING ALL OF THIS. THIS FIRST ONE IS MOVING EAST WITH THE CONVECTION NORTHEAST OF LAKE HURON. THE SECOND IS LESS OBVIOUS BUT IS CURRENTLY OVER THE DAKOTAS AND HEADING EAST OVER THE TOP OF THE UPPER RIDGE. IT IS THAT SHORTWAVE THAT WILL SPARK THE CONVECTION OVER NRN WI AND THE UPPER PENINSULA THIS EVENING INTO THE OVERNIGHT HOURS. THAT CONVECTION WILL DRIVE THE COLD FRONT SOUTH TONIGHT AND MAY BRING THUNDERSTORMS TO OUR NORTHERN CWA BY SUNRISE. THIS LEAD SHORTWAVE CREATES A SORT OF COLD FRONT /WARM FRONT SET UP. SO THE COLD FRONT TRAILING THE LEAD SHORTWAVE IS WHAT DIVES THE CONVECTION SOUTH TONIGHT INTO MONDAY. THEN THE NEXT UPSTREAM WAVE PUSHES IT ALL BACK NORTH AS A WARM FRONT MONDAY NIGHT. THERE IS AN UPPER LEVEL JET ASSOCIATED WITH THIS SO I WOULD EXPECT ANOTHER ROUND OF CONVECTION MONDAY NIGHT INTO TUESDAY MORNING WITH THAT. HOWEVER... IF THE COLD FRONT DOES NOT GET TOO FAR SOUTH MONDAY... THEN MOST OF THE STORMS SHOULD WELL NORTH OF INTERSTATE 96 MONDAY NIGHT. FINALLY THE SHORTWAVE OVER NV CURRENTLY CLIMBS THE UPPER RIDGE AND DIVES DOWN THE FRONT SIDE OF IT TUESDAY AND THAT BRINGS A MORE SIGNIFICANT COLD FRONT THROUGH THE AREA BY EARLY WEDNESDAY. IT IS THAT NV SHORTWAVE THAT I BELIEVE WILL BRING OUR BEST SHOT FOR SIGNIFICANT RAINFALL. THIS WILL LIKELY BE IN THE TUESDAY AFTERNOON INTO TUESDAY NIGHT TIME FRAME. IT WOULD BE THEN THAT THERE WOULD BE THE GREATEST RISK OF STRONG TO SEVERE STORMS. DEEP LAYER SHEAR IS IN THE 30 TO 40 KNOT RANGE DURING THAT TIME AND MIX LAYER CAPES AROUND 1500 J/KG. WITH PRECIPITABLE WATER VALUES NEAR 2 INCHES THERE IS LITTLE QUESTION IF WE GET THUNDERSTORMS MINOR FLOODING OF AREAS WITH POOR DRAINAGE IS A REAL THREAT. AS FOR HOW HOT IT WILL GET... THE 850 TEMPS ARE AROUND 21C MONDAY AND TUESDAY. THAT WOULD SUPPORT HIGHS IN LOWER 90S FOR SURE. ALSO THE 1000/925 MB THICKNESS VALUES SUGGEST MID 90S ACTUALLY. THE ONLY THING THAT WILL KEEP OUR TEMPERATURES FROM GETTING THAT WARM IS IF THERE IS TO MUCH CONVECTIVE DEBRIS CLOUDS AROUND. WHICH IS A REAL PROBLEM FOR THIS FORECAST AS THE COLD FRONT WILL COME CLOSE TO US MONDAY AFTERNOON AND EARLY EVENING. MOS TEMP FORECASTS KEEP HIGHS IN THE 80S BOTH DAY BUT GIVEN HOW WARM THE THICKNESS IS AND 850 TEMPS I HAVE A REAL PROBLEM FORECASTING HIGHS SO LOW. SO WE HAVE TO WAIT AND SEE JUST HOW MUCH CLOUDS GET GENERATED FROM THE UPSTREAM CONVECTION TO SEE HOW HOT IT REALLY GETS THE NEXT TWO DAYS. MEANWHILE I WILL GO WITH HIGHS IN THE LOWER 90S FOR NOW AND CALL THAT GOOD. .LONG TERM...(WEDNESDAY THROUGH SUNDAY) ISSUED AT 350 PM EDT SUN AUG 25 2013 THE GOING MID SUMMER-LIKE FORECAST AND MAINLY DRY CONDITIONS IN THE LONG TERM CONTINUES TO LOOK ON TRACK. WE CONTINUE TO EXPECT THAT THE FRONT SHOULD BE EXITING THE FCST AREA TO THE SOUTH RIGHT AROUND 12Z WED. THIS OCCURS AS THE UPPER HEIGHTS LOWER SLIGHTLY OVER THE AREA...AND NW FLOW ALOFT COMMENCES. THIS WILL RESULT IN DRY CONDITIONS...TEMPS DROPPING A COUPLE OF DEGREES AND SLIGHTLY LOWER HUMIDITY LEVELS AS WE COULD POTENTIALLY SEE ON TUE. H850 TEMPS DROP TO AROUND 18-19C WHICH WOULD STILL SUPPORT HIGHS IN THE MID 80S TO AROUND 90. THE MODELS CONTINUE TO INDICATE SOME SORT OF MCS DEVELOPING TO OUR W LATE THU AND MOVING SE ALONG THE UPPER RIDGE ON FRI. WE HAVE BETTER CONFIDENCE AT THIS TIME THAT THIS COMPLEX WILL END UP SW OF THE AREA CLOSER TO THE BETTER INSTABILITY SOUTH OF THE FRONT. VERY WARM AND DRY CONDITIONS ARE EXPECTED ONCE AGAIN FOR FRI. WE EXPECT TO SEE ANOTHER SURGE OF HEAT THEN BEGINNING NEXT WEEKEND. WE WILL SEE THE UPPER RIDGE AXIS BUILD BACK OVER THE AREA BY NEXT SUN AS SHORT WAVE ENERGY MOVING ACROSS CANADA WILL SHIFT IT E/SE. INCREASING LOW LEVEL SW FLOW AHEAD OF THE SFC LOW WILL HELP TO ADVECT THE HOT TEMPS OVER THE PLAINS OVER OUR AREA. H850 TEMPS ARE FCST TO INCREASE TO THE LOWER 20S C BY NEXT SUN. WE COULD SEE MAX TEMPS WELL INTO THE 90S IF THIS PLAYS OUT THIS WAY. WE HAVE GONE SOMEWHAT CONSERVATIVE FOR NOW WITH HIGHS IN THE LOWER TO MID 90S. THE TRANSITION OF THIS AIR MASS INTO THE AREA COULD BRING A LOW CHC OF PCPN TO THE AREA ON SUN. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 126 PM EDT SUN AUG 25 2013 MAIN ITEMS OF CONCERN IN THE 18Z FCST CYCLE ARE CONVECTIVE CHCS LATE IN THE PERIOD AND WIND GUST TRENDS. THE ONLY CONCERN IN THE FIRST FEW HOURS OF THE 18Z FCSTS WILL BE WIND GUSTS. STRONGER GRADIENT MOVING IN IS HELPING TO PRODUCE WIND GUSTS AS HIGH AS 25 KNOTS THIS AFTERNOON. SOME HIGHER WINDS ARE IN PLACE A COUPLE OF THOUSAND FEET UP DUE TO THE WARMER AIR ADVECTING IN. WE EXPECT THE WIND GUSTS TO DIMINISH AROUND SUNSET TONIGHT OR 00-01Z. VFR CONDITIONS WILL RULE THROUGH THEN WITH ONLY A COUPLE OF PATCHES OF 6K FT CLOUDS AND SOME THIN HIGH CLOUDS OVERHEAD. THE VFR CONDITIONS WILL CONTINUE OVERNIGHT. WE ARE MONITORING THE TRENDS FOR A FEW SHOWERS AND/OR STORMS TO SINK SOUTH INTO THE I-96 TERMINALS EXTREMELY LATE TONIGHT AND ON MON. A FAIR AMOUNT OF UNCERTAINTY REGARDING THIS POTENTIAL PCPN EXISTS AS IT SHOULD BE WANING AS IT APPROACHES. WE BELIEVE IT IS TOO LOW AT THIS POINT IN TIME TO HAVE IN THE FCST PRIOR TO 18Z. WIND GUSTS WILL COME UP ON MON AND CLOUDS WILL BECOME A LITTLE MORE WIDESPREAD. VFR CONDITIONS SHOULD CONTINUE TO RULE UNLESS THE PCPN MAKES IT IN EARLIER. && .MARINE... ISSUED AT 350 PM EDT SUN AUG 25 2013 WITH THE WINDS IN THE BOUNDARY LAYER FORECAST TO BE 20 - 35 KNOTS INTO MONDAY EVENING IT SEEMS MORE THAN REASONABLE TO KEEP THE BEACH HAZARD STATEMENT GOING AND THE SMALL CRAFT ADVISORY. && .HYDROLOGY... ISSUED AT 350 PM EDT SUN AUG 25 2013 WHILE LARGE AREA HEAVY RAINFALL IS NOT EXPECTED... THERE IS LITTLE QUESTION WITH ALL THE PRECIPITABLE WATER OVERHEAD THE NEXT 2-3 DAYS... IF WE DO SEE ANY THUNDERSTORMS SOME VERY HEAVY RAINFALL SHOULD BE EXPECTED AS WELL AS LOCALIZED FLOODING IF THE STORMS MOVE OVER AN URBAN AREA. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...BEACH HAZARDS STATEMENT THROUGH LATE MONDAY NIGHT FOR MIZ037-043- 050-056. LM...SMALL CRAFT ADVISORY UNTIL 6 AM EDT TUESDAY FOR LMZ846>849. && $$ SYNOPSIS...WDM SHORT TERM...WDM LONG TERM...NJJ AVIATION...NJJ HYDROLOGY...WDM MARINE...WDM
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
401 PM CDT SUN AUG 25 2013 .SYNOPSIS... ISSUED AT 359 PM CDT SUN AUG 25 2013 NOT MUCH HAS CHANGED IN THE UPPER LEVELS IN THE LAST 24 HRS...WITH A 598 DM HIGH CENTERED OVER MISSOURI THAT IS STILL FLANKED BY TROUGHS ON EITHER COAST OF NOAM. ACROSS THE ROCKIES...WATER VAPOR IMAGERY IS SHOWING A TROPICAL MOISTURE PLUME FROM THE REMNANTS OF AN ERN PACIFIC TROPICAL SYSTEM CURRENTLY OVER THE BAJA PENINSULA THAT IS NOW WORKING ITS WAY AROUND THE WRN PERIPHERY OF THE MISSOURI HIGHS AND ALREADY MOVING UP INTO WYOMING...LIKELY REACHING THE UPPER MS VALLEY MONDAY. AT THE SFC A TROUGH OF LOW PRESSURE WAS SITUATED FROM CENTRAL SODAK NE TO NEAR INL. STRONG PRESSURE GRADIENT IS STILL IN PLACE...WITH BREEZY SOUTHWEST WINDS CONTINUING. WITH TEMPS IN THE LOW TO MID 90S AND DEWPS IN THE LOW TO MID 70S...STARTING TO SEE HEAT INDICES CLIMB TO OVER 100 DEGREES...WITH VALUES OF MLCAPE UP SAFELY IN THE HEALTHY RANGE BETWEEN 3500 AND 6000 J/KG. && .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 359 PM CDT SUN AUG 25 2013 AS CAN BE IMAGINED...WITH A CAPPED...WEAKLY FORCED...HIGH CAPE ENVIRONMENT...CONFIDENCE IS STILL QUITE LOW ON WHERE/IF CONVECTION WILL FIRE LATER THIS EVENING. ONE THING IS FOR SURE...PRESENCE OF ENOUGH INSTABILITY IS NOT AN ISSUE! WHEN LOOKING AT THE SPC MESO ANALYSIS AND SATELLITE ALONG WITH A FEW INSTABILITY/MOISTURE TRANSPORT FIELDS FROM THE DETERMINISTIC MODELS YOU CAN GET A SENSE OF HOW THINGS SHOULD TRY TO UNFOLD THIS EVENING. FROM THE MESO ANALYSIS SIDE OF THINGS...THERE IS A GRADIENT IN THE MLCAPE FIELD ACROSS CENTRAL MN...WHICH IS COINCIDENT WITH THE NRN EDGE OF THE STEEPER MID LEVEL LAPSE RATES ASSOCIATED WITH AN EML AND STRONGER CAPPING. JUST NORTH OF THE MLCAPE GRADIENT...THE 20Z ANALYSIS SHOWS H7 DEWPOINTS BETTER THAN 10C ACROSS THE SRN END OF THE DLH/FGF FORECAST AREAS. WITHIN THIS ZONE OF HIGHER MOISTURE AT H7 MOISTURE...A SHALLOW CU FIELD HAS DEVELOPED BENEATH A FEW BITS OF ACCUS THAT STRETCH FROM AROUND FERGUS FALLS OVER TOWARD DULUTH. BEST GUESS RIGHT NOW IS THAT IF STORMS ARE TO DEVELOP...IT WILL BE WITHIN THIS ZONE...LIKELY CLOSER TO 00Z. IN ADDITION...MODELS SHOW THE LLJ AND ASSOCIATED MOISTURE ADVECTION VEERING SOME AND SAGGING SOUTH THROUGH THE NIGHT. THE AREA OF CLOUDS REFERENCED ABOVE ALSO SITS ON THE NRN EDGE OF THE MAIN MOISTURE TRANSPORT PLUME AT H85...WHICH MOST GUIDANCE SHOW COMING DOWN TO ABOUT I-94 OVERNIGHT. IF SOMETHING CAN GET GOING...THE PRESENCE OF THE LLJ SHOULD KEEP THE ACTIVITY GOING THROUGH MUCH OF THE NIGHT. WITH THE RAP AND MOST OTHER MODELS SHOWING THE STRONGEST MOISTURE TRANSPORT IN THE H85-H7 LAYER RESIDING OVER ERN MN/WRN WI...CONTINUED TO ADVERTISE LIKELY POPS IN ERN AREAS...THAT TAIL OFF TO LOW CHANCE POPS IN THE WEST FOR TONIGHT. FROM THE SEVERE END OF THINGS...AN ENVIRONMENT ASSOCIATED WITH HIGH MOISTURE CONTENT /PWATS CURRENT NEAR 2 INCHES/...DEEP MELTING LAYERS...AND WEAK SHEAR MEANS LARGE HAIL WILL BE TOUGH TO COME BY. HOWEVER...VALUES OF DCAPE UP AROUND 1500 J/KG INDICATES THE WIND POTENTIAL IS CERTAINLY STILL THERE IF WE CAN GET ANY DEEP MOIST CONVECTION GOING. WHAT HAPPENS TONIGHT WILL GO A LONG WAY IN DETERMINING WHERE ANY POTENTIAL CONVECTION CAN FIRE UP MONDAY AFTERNOON. THE QUESTION FOR TOMORROW IS FAR SOUTH CAN THE BOUNDARY SLOWLY HEADING FOR CENTRAL MN MAKE IT TONIGHT. IF WE DO SEE A GOOD AMOUNT OF CONVECTION OVERNIGHT...THEN THERE IS A GOOD CHANCE THAT THE BOUNDARY CAN MAKE IT DOWN TO ABOUT I-94. IF WE DO NOT SEE MUCH CONVECTION TONIGHT...THEN IN ALL LIKELIHOOD...THE BOUNDARY WILL REMAIN NORTH OF THE MPX AREA...WITH ANOTHER DAY OF CAPED SUNNY SKIES ENSUING. THE NAM/SREF WOULD SUPPORT THE SRN IDEA...WHILE THE GFS/ECMWF/GEM GO NORTH. FOR NOW WENT WITH CHANCE POPS AFTER 21Z FOR AREAS NORTH OF I-94. FROM THE SEVERE PERSPECTIVE...ABOUT THE ONLY THING DIFFERENT ABOUT MONDAY COMPARED TO TODAY IS THAT THE BELT OF STRONGER WESTERLIES WILL HAVE SAGGED SOUTH A BIT MORE...INCREASING THE AMOUNT OF DEEP LAYER SHEAR...WHICH WILL MAKE THE RISK OF LARGE HAIL A BIT HIGHER OWING TO THE CHANCE OF GETTING AT LEAST WEAK SUPERCELL STRUCTURES GOING. LAST STOP IS WITH TEMPERATURES. OVERNIGHT...EXPECT CENTRAL MN TO COOL A FEW DEGREES MORE THAN THEY DID LAST NIGHT AS THE PRESSURE GRADIENT WEAKENS...ALLOWING FOR SOME RADIATIONAL COOLING TONIGHT. STILL...WITH DEWPS AROUND 70...MOST PLACES SHOULD STILL STAY ABOVE THAT MARK. FOR THE TWIN CITIES AND PLACES FARTHER SOUTH/EAST...WINDS WILL REMAIN IN PLACE /THOUGH NOT AS STRONG AS LAST NIGHT/...WHICH WILL KEEP SOME FORM OF MIXING GOING AND ONCE AGAIN MAKE IT A STRUGGLE FOR A LOT OF PLACES TO DROP BELOW 80 WITHOUT THE HELP OF RAIN. FOR HIGHS TOMORROW...925-850 MB TEMPS ACTUALLY INCREASE A DEGREE OR TWO AS COMPARED TO TODAY...WHICH WOULD THEORETICALLY MEAN WE COULD GET A DEGREE OR TWO WARMER. HOWEVER...THERE IS THE POTENTIAL FOR A BIG BUST WITH HIGHS TOMORROW DEPENDING ON WHAT HAPPENS WITH STORMS TONIGHT. IF WE DO END UP SEEING FAIRLY WIDESPREAD AND ROBUST CONVECTION OVERNIGHT...THIS WOULD LIKELY LEAVE BEHIND PLENTY OF DEBRIS COLD COVER...PUTTING A DAMPER ON TEMPERATURES. THE HIRES NMM EAST DOES EXACTLY THAT WITH CONVECTION OVERNIGHT. THE RESULTING CLOUD COVER IT GENERATED FOR THE NEXT DAY RESULTED IN IT ONLY GENERATING HIGHS IN THE MID/UPPER 80S. AT THE OTHER END OF THE SCALE...A NIGHT OF LITTLE CONVECTION WILL RESULT IN ANOTHER DAY OF LOTS OF SUN. IN THAT CASE...THEN HIGHS TOMORROW WOULD BE A DEGREE OR TWO WARMER THAN TODAY...WITH HIGHS IN THE MID/UPPER 90S AND A FEW 100 DEGREE READINGS NOT OUT OF THE QUESTION IN WRN MN. AT ANY RATE...DID NOT SEE ANYTHING GLARING CHANGE WITH THE TEMP FORECAST TODAY THAT REQUIRED ANY CHANGES IN THE GOING HEAT HEADLINES. .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) ISSUED AT 359 PM CDT SUN AUG 25 2013 LONG TERM TRENDS CONTINUE TO SHOW HOT AND HUMID CONDITIONS WILL CONTINUE THROUGH AT LEAST TUESDAY. LOCATION OF FRONTAL BOUNDARY MONDAY NIGHT WILL DETERMINE TO WHAT EXTENT/LOCATION CONVECTIVE ACTIVITY WILL DEVELOP OVER THE CWA. VARIOUS DETERMINISTIC MODELS SHOW THIS BOUNDARY LIFTING SLOWLY BACK NORTH MONDAY NIGHT AND INTO TUESDAY AS WEAK COOL FRONT/SURFACE LOW MOVES THROUGH THE AREA. WILL CONTINUE THE CHANCE POPS OVER THE NORTHEAST THIRD OF THE AREA FOR TUESDAY...WHICH SHOULD EXIT THE CWA BY TUESDAY EVENING. EXPECT TEMPERATURES TO RANGE IN THE MID/SOME UPPER 90S AND DEWPOINTS POOLING AHEAD OF BOUNDARY INTO THE LOWER 70S. HEAT INDEX VALUES WILL RANGE 100F TO 105F WITH THE CURRENT HEAT ADVISORY/WARNING STILL LOOKING GOOD CONTINUING THROUGH TUESDAY. SOME COOLING BEHIND THE FRONT LINGERING INTO FRIDAY...MAINLY OVER THE EASTERN PORTION OF THE CWA. RIDGING ALOFT DEVELOPS THEREAFTER WITH SURFACE FRONT MEANDERING OVER CENTRAL MINNESOTA AGAIN INTO THE WEEKEND. THE 12Z ECMWF IS SLOWER BUILDING THE UPPER RIDGE TO THE EAST...WITH THE MAIN SURGE COMING NEXT SUNDAY. THE GFS BUILDS IN NORTH BY SATURDAY. WILL GO ALONG WITH PRESENT TREND OF BRINGING THE 90S BACK INTO THE AREA FOR SATURDAY AND SUNDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 1249 PM CDT SUN AUG 25 2013 BIGGEST SOURCE OF UNCERTAINTY REMAINS WITH IF/WHERE CONVECTION WILL BE THIS EVENING/OVERNIGHT. LOOKING AT WHERE THE WEAK SFC TROUGH MENTIONED IN THE UPDATE IS EXPECTED TO BE...ALONG WITH FORECAST LLJ PLACEMENT...PROBABILITY FOR SEEING CONVECTION TONIGHT WILL BE BEST ALONG/NORTH OF 94. CONFIDENCE IN STORMS TONIGHT STILL LOW ENOUGH THAT HELD ANY TS MENTION TO A VC OR PROB30. WITH THAT TROUGH SETTLING INTO CENTRAL MN OVERNIGHT...WINDS THERE WILL CALM DOWN CONSIDERABLY...AND WITH DEWPOINTS IN THE UPPER 60S/LOWER 70S HZ/BR WILL LIKELY BECOME AN ISSUE TOWARD SUNRISE THERE. KMSP...12Z TAF STILL LOOKED GOOD FOR TIMING OF ANY CONVECTION THIS EVENING. CONFIDENCE HAS NOT INCREASED ENOUGH TO GO WITH ANYTHING MORE THAN THE PROB30 AT THIS POINT. IF WE DO NOT SEE ANY CONVECTION OVERNIGHT...THEN THE HIGH MOISTURE CONTENT AT LOWER LEVELS WILL LIKELY LEAD TO SOME MINOR ISSUES WITH HAZE MONDAY MORNING. ANY CONVECTION POSSIBILITIES MONDAY AFTERNOON WILL DEPEND HEAVILY ON HOW FAR SOUTH ANY CONVECTION TONIGHT CAN PUSH THE BOUNDARY HEADING FOR CENTRAL MN. THIS FAR OUT...HAVE LEFT ANY ADDITIONAL TS MENTION OUT...BUT WILL BE SOMETHING TO KEEP AN EYE ON. /OUTLOOK FOR KMSP/ TUE...VFR. WIND SW 5-10 KT...BECOMING W/NW IN AFTERNOON. WED...VFR. WIND NE 5 KT. THU...VFR. ISOLD SHRA/TS POSSIBLE. WINDS SE 5 KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...EXCESSIVE HEAT WARNING UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR MNZ054>070-073>078-082>085-091>093. HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR MNZ041>045- 047>053. WI...HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR WIZ014>016- 023>028. && $$ SYNOPSIS...MPG SHORT TERM...MPG LONG TERM...DWE AVIATION...MPG
AREA FORECAST DISCUSSION
NWS DULUTH MN
1242 PM CDT SUN AUG 25 2013 .UPDATE... HAVE JUST SENT OUT AN UPDATE TO ACCOUNT FOR RECENT AND EXPECTED CONVECTIVE TRENDS. INSTABILITY IS BUILDING ACROSS THE REGION TODAY WITH MARGINAL SHEAR OF 30 TO 40 KTS. WE ALSO HAVE A FAIRLY DECENT CAP...WITH 700MB TEMPS OF 10C PLUS OVER MOST OF THE FORECAST AREA. WE ARE GOING TO NEED A DECENT TRIGGER TO GET PAST ALL THAT. SURFACE FEATURES AT THIS TIME ARE A LITTLE TOO WEAK...BUT THERE IS A WEAK SHORTWAVE ON VISIBLE SATELLITE IMAGERY OVER NORTHERN SOUTH DAKOTA...ASSOCIATED WITH A WEAK ENHANCEMENT ON WV SATELLITE IMAGERY THAT MAY PROVIDE JUST ENOUGH LIFT TO GENERATE STORMS. IT SHOULD BE MOVING INTO THE SOUTHWESTERN PORTIONS OF THE FORECAST AREA AROUND 01Z THIS EVENING. IT WILL BE MOVING OVER THE VERY UNSTABLE AIRMASS OVER EASTERN SOUTH DAKOTA HERE IN THE NEXT FEW HOURS...SO IF IT IS GOING TO BE ABLE TO GENERATE CONVECTION WE SHOULD KNOW SOON. && .PREV DISCUSSION... /ISSUED 729 AM CDT SUN AUG 25 2013/ AVIATION...12Z TAF ISSUANCE... STORMS WILL MOVE NEAR THE KHIB SITE EARLY MORNING SO HAVE INCLUDED A VCTS THRU 14Z. OTHERWISE VFR CONDITIONS ARE EXPECTED TODAY. A WEAK FRONT.. OR WINDSHIFT BDRY... WILL SINK SOUTH LATER TODAY FROM THE BORDERLAND TOWARDS THE TWIN PORTS. THUNDERSTORMS ARE POSSIBLE ALONG THIS BDRY LATER TODAY AND CONTINUING THIS EVENING. THERE IS A POSSIBILITY THAT THE CONVECTION MAY HAVE A TOUGH TIME INITIATING GIVEN THE EXTENT OF WARM AIR ALOFT. GIVEN LOWER CONFIDENCE IN CONVECTION WE WILL USE PROB 30 BEGINNING LATE TODAY AT KBRD/KDLH/KHYR TERMINALS. MAJORITY OF CONVECTION IS EXPECTED TO REMAIN SOUTH OF KINL THIS PERIOD. PREV DISCUSSION... /ISSUED 604 AM CDT SUN AUG 25 2013/ UPDATE... WE`VE HAD TO UPDATE GRIDS/PRODUCTS THIS MORNING TO ADD MORE SHOWERS/STORMS ACROSS THE NORTHLAND FOR THE NEXT FEW HOURS. RADAR HAS SHOWN AN INCREASE IN COVERAGE OVER CENTRAL MINNESOTA AND OVER CROW WING/AITKIN COUNTIES. SOME STRONG STORMS WILL REMAIN POSSIBLE FOR A COUPLE MORE HOURS. THE LATEST 08Z HRRR AS WELL AS THE NMM/ARW HIRES MODELS SUGGEST MUCH OF THESE SHOWERS/STORMS WILL DISSIPATE BY MID-LATE MORNING. HOWEVER...CONFIDENCE IN THIS OCCURRING IS LOWER THAN NORMAL SINCE THEY ARE NOT DOING A GOOD JOB WITH THE CURRENT CONVECTION. PREV DISCUSSION... /ISSUED 349 AM CDT SUN AUG 25 2013/ SHORT TERM...THROUGH EARLY MONDAY EVENING. HOT AND HUMID CONDITIONS WILL COVER MUCH OF THE NORTHLAND TODAY. THE LARGE UPPER HIGH OVER THE CENTRAL CONUS WILL REMAIN THROUGH THE SHORT TERM...WITH A COUPLE DIFFERENT FEATURES MOVING THROUGH BRINGING A THREAT FOR SHOWERS/STORMS. AS OF 0830Z...A FEW THUNDERSTORMS WERE OCCURRING OVER FAR NORTHERN MINNESOTA DUE TO A PASSING WAVE AND WAA WITH SOUTHWESTERLY LLJ. KDLH`S VWP SHOWED 35 KT AT 925MB WITH WEST WINDS AT 850MB OF 50 KT. STRONG THUNDERSTORMS WERE OCCURRING OVER EASTERN NORTH DAKOTA IN AN AREA OF LOW LEVEL CONVERGENCE ALONG A WEAK FRONTAL BOUNDARY. THE AIRMASS IS PLENTY UNSTABLE THIS MORNING WITH MUCAPES OF 1000-2000J/KG AND MLCAPES OF 500-1500J/KG. WARM LOW-MID LEVEL TEMPS COVERED THE CWA...WITH THE MODELS SHOWING 700MB TEMPS OF +10 TO +12C. THE 00Z KINL SOUNDING HAD +11C AT 700MB. WE EXPECT THE NORTHERN MINNESOTA SHOWERS/STORMS TO CONTINUE EAST EARLY THIS MORNING...WITH SOUTHWARD DEVELOPMENT LOOKING LESS LIKELY. THE LOW LEVEL CONVERGENT AREA AS FORECAST BY THE RAP AT 925MB...MAY ALLOW FOR SOME ADDITIONAL DEVELOPMENT OVER PORTIONS OF OUR WEST/SOUTHWEST PRIOR TO 12Z...BUT MORE LIKELY AFTER THAT TIME. THERE WILL BE A BATTLE BETWEEN THE LIFT FROM THE APPROACHING TROUGH AND THE WARM MID LEVEL TEMPS TODAY. WE DO KEEP SOME LOW POPS OVER CENTRAL PORTIONS OF THE CWA...THEN INCREASE FURTHER LATER THIS AFTERNOON WITH MAX HEATING...THE LOW LEVEL TROUGH AND PERHAPS A WEAK WAVE ALL CONTRIBUTING TO LIFT. THE STORMS COULD BE SEVERE OVER THE SOUTHERN HALF OF THE NORTHLAND THIS AFTERNOON INTO TONIGHT. WE STILL EXPECT HIGHS TO REACH THE LOWER TO MIDDLE NINETIES OVER MUCH OF THE NORTHLAND. IT WILL BE HUMID WITH DEWPOINTS IN THE UPPER SIXTIES TO LOWER SEVENTIES. WE KEPT THE HEAT ADVISORY THE SAME. AREAS AROUND LAKE SUPERIOR...EXCEPT FOR PERHAPS UP INTO COASTAL COOK COUNTY...WILL ALSO BE HOT TODAY DUE TO OFFSHORE WINDS. MONDAY WILL REMAIN HOT WITH HIGHS FROM THE UPPER EIGHTIES TO LOWER NINETIES. AREAS ALONG LAKE SUPERIOR WILL BE COOLER THOUGH...AS AN ONSHORE FLOW DEVELOPS DUE TO LOW PRESSURE OUT TO THE WEST AND A WEAK HIGH TO THE EAST. A WARM FRONT WILL BE DRAPED FROM WEST TO EAST ACROSS THE NORTHLAND. WE INTRODUCED SOME POPS ALONG THIS FEATURE OVER ALL BUT FAR NORTHERN MINNESOTA ON MONDAY. CONVERGENCE IS WEAK...BUT WE CAN`T RULE OUT SOME THUNDERSTORM DEVELOPMENT WITH PEAK HEATING. LONG TERM...MONDAY NIGHT THROUGH SUNDAY. A LARGE SFC/MID LVL RIDGE WILL PREVAIL OVER THE SRN PLAINS THROUGH THE WEEK WITH UNUSUALLY HOT AND MUGGY WEATHER EXPECTED ACROSS THE NORTHLAND. THE HEAT WILL BE TEMPERED BRIEFLY BY THE PASSAGE OF A FRONTAL SYSTEM MON NIGHT AND EARLY TUESDAY. THIS WILL BE THE BEST CHANCE FOR MUCH NEEDED PRECIP ACROSS THE CTRL/SRN CWA. HOWEVER...THE PRESENCE OF THE ANOMALOUS RIDGE AT MID LVLS WITH AN ASSOCIATED MID LVL WARM LAYER MAKES THE CONVECTIVE OPPORTUNITIES QUESTIONABLE. MOST LIKELY AREA WILL BE NRN MN ZONES AHEAD OF WARM FRONTAL BDRY MONDAY NIGHT AND ON NRN FRINGES OF NORTHWARD ADVECTING MID LVL CAP. SFC COLD FRONT WILL PASS THROUGH TUESDAY HOWEVER EXTENSIVE CIN IS EXPECTED BY EARLY AFTN SO POPS LOWERED. HIGH PRESSURE IS EXPECTED TO PASS ACROSS THE AREA WED/WED NIGHT. A TEMPORARY REDUCTION IN HUMIDITY SHOULD OCCUR BEFORE SFC HIGH MOVES EAST THURSDAY. HEAT/HUMIDITY INCREASE LATE WEEK INTO WEEKEND AS WARM ADVECTION RESUMES. LOW POPS LATE WEEK AND INTO WEEKEND AS UPPER JET REMAINS NORTH OF CWA AND MAIN CONVECTION CHANCES ARE POSITIONED NORTH AND WEST OF CWA. && .POINT TEMPS/POPS... DLH 69 89 68 87 / 50 40 50 40 INL 61 88 67 86 / 0 40 60 30 BRD 69 94 72 91 / 50 40 50 20 HYR 71 92 71 92 / 60 50 50 30 ASX 69 85 68 86 / 50 40 50 50 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...HEAT ADVISORY UNTIL 9 PM CDT MONDAY FOR MNZ033>038. WI...HEAT ADVISORY UNTIL 9 PM CDT MONDAY FOR WIZ001>004-006>009. LS...NONE. && $$ SHORT TERM...LE
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
256 PM EDT SUN AUG 25 2013 .SYNOPSIS... AN APPROACHING FRONTAL SYSTEM WILL BRING SCATTERED SHOWERS AND THUNDERSTORMS LATE TONIGHT AND MONDAY. DRY WEATHER IS FORECAST FOR TUESDAY...BUT MORE SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE TUESDAY NIGHT AND WEDNESDAY AS ANOTHER COLD FRONT MOVES THROUGH THE REGION. AFTER THIS FRONT PASSES BY...FAIR WEATHER IS EXPECTED FOR THURSDAY AND FRIDAY. && .NEAR TERM /THROUGH MONDAY/... UDPATED THE NEAR TEAM TO BRING POPS IN ERLR FROM THE MCS THAT IS MOVING ACRS ONT AND QUE AND THE NERN GREAT LAKES. THE HRRR HAS BEEN SHOWING THAT THIS PRECIP WILL GET INTO NC AND EC NY BETWEEN 1Z AND 6Z WITH THE RAP NOW SPEEDING THE ARRIVAL UP TOO OVER THE OTHER MODELS. SINCE THESE ARE RAPID UPDATE CYCLE MODELS AND THE RADAR TRENDS ARE CLSR TO THESE MODELS I NOW BRING IN PRECIP MUCH ERLR IN LINE WITH KBUF/S RECENT UPDATE. OTHERWISE...NO OTHER CHANGES THRU MONDAY. PREVIOUS DSCN BELOW... VISIBLE SATL IMAGERY SHOWS SCT CUMULUS FORMING WITH INSOLATION. SOME CIRRUS FROM AN UPSTREAM MCS OVER NRN AND CNTRL ONTARIO AND THE UPPER LAKES WILL STREAM SOUTHEASTWARD FOR THE REST OF THE AFTERNOON....THUS SKIES WILL BE PS TO MS. CANADIAN RADAR LOOP SHOWS AN MCS WITH SHOWERS AND THUNDERSTORMS TRACKING SEWRD ACRS GEORGIAN BAY AND TWD SERN ONTARIO INTO WRN QUEBEC. CONVECTION ALLOWING MESOSCALE MODELS ...WRF-NMM, WRF-ARW AND HRRR ALL SHOW THE SRN EDGE OF THE PRECIPITATION SHIELD WITH THIS MCS SKIRTING ACRS NRN AND ERN NY TONIGHT WITH ELEVATED INSTABILITY REMAINING ON THE BACK EDGE OF THE MCS AS IT WORKS SEWRD. THE MAIN QUESTION IS TIMING. LATEST WRF-NMM AND WRF-ARW BOTH HAVE SHRA AND TSRA ARRIVING AFTER 6Z...MAINLY 9-12Z ACRS NC NY SEWRD TO THE CATSKILLS. THE HRRR ON THE OTHER HAND HAS THE PRECIP SHIELD AND SOME TSRA ARRIVING MUCH ERLR...SPREADING FROM NC NY SOUTHWARD TO THE CATSKILLS AND EVEN NE PA BETWEEN 1Z AND 6Z ABT 4-6 HOURS SOONER. TTHE NAM...GFS AND CANADIAN ALL BRING SOME LIGHT PRECIP INTO THESE AREAS LATE TONIGHT WITH THE RUC A LITTLE FASTER ON THE ARRIVAL OF THE PRECIP. THUS THE HRRR AND THE RUC TO A LESSER EXTENT AERE ON AN ISLAND BY THEMSELVES. HOWEVER...JUDGING BY LATEST RADAR LOOP IT LOOKS LIKE THE HRRR HAS THE BEST HANDLE...BUT THIS IS A MAJOR DEPARTURE FROM ERLR FCSTS AND ALL OTHER MODEL GUIDC AND SOUNDINGS INDICATE THAT IT IS VERY DRY BELOW 10000 FEET. SO FOR NOW WILL HAVE CHC POPS NRN AND ERN CWA INCREASING AFTR 6Z...BUT WILL RE-EVALUATE AND MAY HAVE TO BUMP UP POPS ERLR. I WUD LIKE TO SEE RADAR TRENDS ON THE SRN EDGE OF THIS MCS AND IF THE PRECIP IS REACHING THE GRND NEXT COUPLE HOURS. FOR MONDAY...AN UPPER LEVEL WAVE WILL MOVE EASTWARD TWD NY AND PA IN THE NW UPPER LEVEL FLO PATTERN. CONVECTION ALLOWING MODELS...ESPECIALLY THE WRF-NMM, AND WRF-ARW AS WELL AS THE NAM AND HIGHER RES CANADIAN ALL INDICATE SOME POTENTIAL FOR TRAINING THUNDERSTORMS AS THE LL FLOW WILL BE W-NW AND FAIRLY ALIGNED WITH THE UPPER LEVEL FLO. BOTH THE CANADIAN AND NAM HAVE A WELL DEVELOPED JET ENTRANCE REGION CIRCULATION FOR OUR AREA WHEREAS THE ERLR EURO AND 12Z GFS REALLY DON/T. MODEL CAPES ARE AVERAGING ARND 1000 J/KG OR SO WITH MODEST SHEAR VALUES...GENERALLY 25 TO 30 KNOTS IN THE LOWEST 6 KM WITH MOST OF THE SHEAR ACTUALLY BETWEEN 0 AND 3 KM. I CAN EASILY SEE AN MCS EVOLVING OVER OUR REGION MON PM AND...IN ITS WAKE SOME TRAINING STORMS WITH LOCALLY HEAVY RAINS. FOR NOW...THINK LIKELY POPS ARE ON ORDER MON PM. THERE IS WAY TOO MUCH UNCERTAINTY AS TO HEAVY RAINFALL POTENTIAL. NAM AND CMC GIVE THE REGION A STRIPE OF 1-2 INCHES OF RAIN WHICH SHUDN/T BE MUCH OF A PROBLEM AT ALL. HOWEVER WILL ALERT FUTURE SHIFTS FOR POTENTIAL TO RAISE SITUATIONAL AWARENESS. AS FOR SEVERE POTENTIAL...THERE CUD BE SOME LOCALLY DAMAGING WINDS...BUT AT THIS POINT IT LOOKS LIKE THE CAPE AND SHEAR FALL SHORT OF WHAT WE WOULD EXPECT FOR AN OUTBREAK. SPC CONCURS IN THEIR DAY 2 OUTLOOK. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/... I KEPT TUESDAY DRY AS NY AND PA IS IN BETWEEN SYSTEMS WITH A SMALL BUBBLE HIGH OVERHD. ALL SYNOPTIC MODELS INDICATE THAT THE MAJORITY OF THE DAY IS DRY WITH JUST A FEW HUNDRENTHS POSSIBLE IN THE SW AND FAR NE PART OF OUR CWA. FOR WEDNESDAY...MODELS ARE IN AGREEMENT THAT ANOTHER MCS AND SHRT WAVE WILL AFFECT THE REGION. MODEL TIMING AND PLACEMENT IS UNCERTAIN THIS FAR OUT. SO I HAVE GENERIC CHC POPS FOR SHRA AND TSRA TO COVER IN LINE WITH NEIGHBORING OFFICES. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... NO MAJOR CHANGES TO THIS PART OF THE FORECAST. THE BROAD...AND HOT LATE SEASON RIDGE OVER MUCH OF THE WESTERN AND CNTRL CONUS IS STILL EXPECTED TO EXPAND INTO THE NORTHEAST BY THE END OF THE PERIOD WITH REGIONAL HIGH TEMPERATURES EXPECTED TO RISE WELL INTO THE MID 80S OVER NEXT WEEKEND. THE ADVERTISED FRONTAL SYSTEM...POSSIBLY ACCOMPANIED BY A COMPLEX SECONDARY LOW DEVELOPMENT ON THE BOUNDARY...IS STILL FORECAST TO BE MOVING EAST OF THE AREA IN THE WEDNESDAY NIGHT-THURSDAY TIME FRAME. THE FORECAST WILL STILL FEATURE DECREASING POPS WITH TIME INTO THURSDAY...THEN WITH THE BROAD RIDGE IN PLACE THURSDAY NIGHT AND NEXT WEEKEND LOOKS RAIN FREE AND WARMER AT THIS TIME. && .AVIATION /19Z SUNDAY THROUGH FRIDAY/... FOR A GENERALLY VFR SITUATION...THIS FORECAST HAS SOME INTERESTING WRINKLES BUILT IN. A RATHER STUBBORN THUNDERSTORM COMPLEX MOVING THROUGH THE UPPER GREAT LAKES REGION THIS AFTERNOON LOOKS TO BE TARGETING OUR TERMINALS FOR THIS EVENING. THE SYSTEM WILL LOSE A LOT OF IT`S CONVECTIVE PUNCH AS IT PULLS AWAY FROM THE SOURCE REGION OF BEST INSTABILITY OVER THE UPPER MIDWEST AND WESTERN ONTARIO...BUT WILL STILL LIKELY BRING IN SOME MID LVL CIGS AND POSSIBLE SHOWERS. LINEAR EXTRAPOLATION BRINGS THE LEADING EDGE OF SYSTEM INTO THE KSYR-KRME-KITH AREAS TOWARD 00Z WITH SHOWER POTENTIAL FOR A FEW HOURS THEREAFTER. NOT SURE IF MUCH RAIN WILL REACH THE GROUND AS LAYERS BETWEEN 5K-10K FT ARE PRETTY DRY. COULD TURN OUT TO BE JUST INSIGNIFICANT -SHRA FROM THE MID DECK. LATER ON TONIGHT...THE SWLY FLOW ALOFT DOES TEND TO MOISTEN UP THE LOWER LEVELS OF THE ATMOSPHERE WITH CIGS PROBABLY LOWERING INTO THE 5 KFT RANGE BY MORNING. THERE STANDS TO BE ANOTHER ROUND OF SHOWERS DEVELOPING TOWARD MORNING AS MINOR UPPER LEVEL IMPULSES MOVE THROUGH THE NORTHWESTERLY JET LEVEL FLOW. MVFR SHOULD BE LIMITED TO MAYBE SOME LIGHT FOG AT KELM...ALTHOUGH THERE IS SOME CHANCE FOR LOWER CIGS IN ANY RAIN SHOWERS, BUT THE CONFIDENCE FOR INCLUDING THAT IN THE FORECAST IS PRETTY LOW. WINDS GENERALLY LIGHT SOUTHWEST...OR VARIABLE DRAINAGE FLOW IS EXPECTED THROUGH TONIGHT...THEN INCREASING SW-W UP TO 10 KTS ON MONDAY. OUTLOOK... MON...VFR. OCNL SHRA. CHC TSRA IN PM. TUE...VFR. CHC SHRA/TSRA PM. LOCAL MVFR. WED...VFR. SHRA/TSRA LIKELY. CHC MVFR. THU...VFR. FRI...VFR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...DJN NEAR TERM...DJN SHORT TERM...DJN LONG TERM...JAB AVIATION...JAB
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
226 PM EDT SUN AUG 25 2013 .SYNOPSIS... AN APPROACHING FRONTAL SYSTEM WILL BRING SCATTERED SHOWERS AND THUNDERSTORMS LATE TONIGHT AND MONDAY. DRY WEATHER IS FORECAST FOR TUESDAY...BUT MORE SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE TUESDAY NIGHT AND WEDNESDAY AS ANOTHER COLD FRONT MOVES THROUGH THE REGION. AFTER THIS FRONT PASSES BY...FAIR WEATHER IS EXPECTED FOR THURSDAY AND FRIDAY. && .NEAR TERM /THROUGH MONDAY/... VISIBLE SATL IMAGERY SHOWS SCT CUMULUS FORMING WITH INSOLATION. SOME CIRRUS FROM AN UPSTREAM MCS OVER NRN AND CNTRL ONTARIO AND THE UPPER LAKES WILL STREAM SOUTHEASTWARD FOR THE REST OF THE AFTERNOON....THUS SKIES WILL BE PS TO MS. CANADIAN RADAR LOOP SHOWS AN MCS WITH SHOWERS AND THUNDERSTORMS TRACKING SEWRD ACRS GEORGIAN BAY AND TWD SERN ONTARIO INTO WRN QUEBEC. CONVECTION ALLOWING MESOSCALE MODELS ...WRF-NMM, WRF-ARW AND HRRR ALL SHOW THE SRN EDGE OF THE PRECIPITATION SHIELD WITH THIS MCS SKIRTING ACRS NRN AND ERN NY TONIGHT WITH ELEVATED INSTABILITY REMAINING ON THE BACK EDGE OF THE MCS AS IT WORKS SEWRD. THE MAIN QUESTION IS TIMING. LATEST WRF-NMM AND WRF-ARW BOTH HAVE SHRA AND TSRA ARRIVING AFTER 6Z...MAINLY 9-12Z ACRS NC NY SEWRD TO THE CATSKILLS. THE HRRR ON THE OTHER HAND HAS THE PRECIP SHIELD AND SOME TSRA ARRIVING MUCH ERLR...SPREADING FROM NC NY SOUTHWARD TO THE CATSKILLS AND EVEN NE PA BETWEEN 1Z AND 6Z ABT 4-6 HOURS SOONER. TTHE NAM...GFS AND CANADIAN ALL BRING SOME LIGHT PRECIP INTO THESE AREAS LATE TONIGHT WITH THE RUC A LITTLE FASTER ON THE ARRIVAL OF THE PRECIP. THUS THE HRRR AND THE RUC TO A LESSER EXTENT AERE ON AN ISLAND BY THEMSELVES. HOWEVER...JUDGING BY LATEST RADAR LOOP IT LOOKS LIKE THE HRRR HAS THE BEST HANDLE...BUT THIS IS A MAJOR DEPARTURE FROM ERLR FCSTS AND ALL OTHER MODEL GUIDC AND SOUNDINGS INDICATE THAT IT IS VERY DRY BELOW 10000 FEET. SO FOR NOW WILL HAVE CHC POPS NRN AND ERN CWA INCREASING AFTR 6Z...BUT WILL RE-EVALUATE AND MAY HAVE TO BUMP UP POPS ERLR. I WUD LIKE TO SEE RADAR TRENDS ON THE SRN EDGE OF THIS MCS AND IF THE PRECIP IS REACHING THE GRND NEXT COUPLE HOURS. FOR MONDAY...AN UPPER LEVEL WAVE WILL MOVE EASTWARD TWD NY AND PA IN THE NW UPPER LEVEL FLO PATTERN. CONVECTION ALLOWING MODELS...ESPECIALLY THE WRF-NMM, AND WRF-ARW AS WELL AS THE NAM AND HIGHER RES CANADIAN ALL INDICATE SOME POTENTIAL FOR TRAINING THUNDERSTORMS AS THE LL FLOW WILL BE W-NW AND FAIRLY ALIGNED WITH THE UPPER LEVEL FLO. BOTH THE CANADIAN AND NAM HAVE A WELL DEVELOPED JET ENTRANCE REGION CIRCULATION FOR OUR AREA WHEREAS THE ERLR EURO AND 12Z GFS REALLY DON/T. MODEL CAPES ARE AVERAGING ARND 1000 J/KG OR SO WITH MODEST SHEAR VALUES...GENERALLY 25 TO 30 KNOTS IN THE LOWEST 6 KM WITH MOST OF THE SHEAR ACTUALLY BETWEEN 0 AND 3 KM. I CAN EASILY SEE AN MCS EVOLVING OVER OUR REGION MON PM AND...IN ITS WAKE SOME TRAINING STORMS WITH LOCALLY HEAVY RAINS. FOR NOW...THINK LIKELY POPS ARE ON ORDER MON PM. THERE IS WAY TOO MUCH UNCERTAINTY AS TO HEAVY RAINFALL POTENTIAL. NAM AND CMC GIVE THE REGION A STRIPE OF 1-2 INCHES OF RAIN WHICH SHUDN/T BE MUCH OF A PROBLEM AT ALL. HOWEVER WILL ALERT FUTURE SHIFTS FOR POTENTIAL TO RAISE SITUATIONAL AWARENESS. AS FOR SEVERE POTENTIAL...THERE CUD BE SOME LOCALLY DAMAGING WINDS...BUT AT THIS POINT IT LOOKS LIKE THE CAPE AND SHEAR FALL SHORT OF WHAT WE WOULD EXPECT FOR AN OUTBREAK. SPC CONCURS IN THEIR DAY 2 OUTLOOK. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/... LINGERING SHRA/TSRA PSBL MON EVNG AS FNTL SYSTEM DEPARTS AND WEAK HI PRES BUILDS INTO THE RGN. NAM/GFS PROFILES BOTH SHOW FAIRLY SIG LOW LVL MSTR BEHIND THIS BNDRY PERSISTING INTO TUE MRNG...WHICH SHUD BURN OFF BY LATE MRNG LEAVING PS SKIES. THE NXT S/WV AND FNTL SYSTEM APRCHS TUE NGT. ALL MDLS SUGGEST MCS POTNL BUT THERE ARE SIG DIFFS W/RESPECT TO THE TRACK OF THE SFC LOW/MCS. GFS/NAM SUGGEST A MORE SWD TRACK OF THE LOW AND MCS...WHILE THE EURO/GEM INDICATE A MORE NRLY TRACK. NO DOUBT LATER FCSTS WILL BE TWEAKED AS WE GET CLOSER TO THE EVENT...SO FOR NOW WENT WITH MOS POPS (CHC) FOR THESE TIME PDS. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... NO MAJOR CHANGES TO THIS PART OF THE FORECAST. THE BROAD...AND HOT LATE SEASON RIDGE OVER MUCH OF THE WESTERN AND CNTRL CONUS IS STILL EXPECTED TO EXPAND INTO THE NORTHEAST BY THE END OF THE PERIOD WITH REGIONAL HIGH TEMPERATURES EXPECTED TO RISE WELL INTO THE MID 80S OVER NEXT WEEKEND. THE ADVERTISED FRONTAL SYSTEM...POSSIBLY ACCOMPANIED BY A COMPLEX SECONDARY LOW DEVELOPMENT ON THE BOUNDARY...IS STILL FORECAST TO BE MOVING EAST OF THE AREA IN THE WEDNESDAY NIGHT-THURSDAY TIME FRAME. THE FORECAST WILL STILL FEATURE DECREASING POPS WITH TIME INTO THURSDAY...THEN WITH THE BROAD RIDGE IN PLACE THURSDAY NIGHT AND NEXT WEEKEND LOOKS RAIN FREE AND WARMER AT THIS TIME. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... FOR A GENERALLY VFR SITUATION...THIS FORECAST HAS SOME INTERESTING WRINKLES BUILT IN. A RATHER STUBBORN THUNDERSTORM COMPLEX MOVING THROUGH THE UPPER GREAT LAKES REGION THIS AFTERNOON LOOKS TO BE TARGETING OUR TERMINALS FOR THIS EVENING. THE SYSTEM WILL LOSE A LOT OF IT`S CONVECTIVE PUNCH AS IT PULLS AWAY FROM THE SOURCE REGION OF BEST INSTABILITY OVER THE UPPER MIDWEST AND WESTERN ONTARIO...BUT WILL STILL LIKELY BRING IN SOME MID LVL CIGS AND POSSIBLE SHOWERS. LINEAR EXTRAPOLATION BRINGS THE LEADING EDGE OF SYSTEM INTO THE KSYR-KRME-KITH AREAS TOWARD 00Z WITH SHOWER POTENTIAL FOR A FEW HOURS THEREAFTER. NOT SURE IF MUCH RAIN WILL REACH THE GROUND AS LAYERS BETWEEN 5K-10K FT ARE PRETTY DRY. COULD TURN OUT TO BE JUST INSIGNIFICANT -SHRA FROM THE MID DECK. LATER ON TONIGHT...THE SWLY FLOW ALOFT DOES TEND TO MOISTEN UP THE LOWER LEVELS OF THE ATMOSPHERE WITH CIGS PROBABLY LOWERING INTO THE 5 KFT RANGE BY MORNING. THERE STANDS TO BE ANOTHER ROUND OF SHOWERS DEVELOPING TOWARD MORNING AS MINOR UPPER LEVEL IMPULSES MOVE THROUGH THE NORTHWESTERLY JET LEVEL FLOW. MVFR SHOULD BE LIMITED TO MAYBE SOME LIGHT FOG AT KELM...ALTHOUGH THERE IS SOME CHANCE FOR LOWER CIGS IN ANY RAIN SHOWERS, BUT THE CONFIDENCE FOR INCLUDING THAT IN THE FORECAST IS PRETTY LOW. WINDS GENERALLY LIGHT SOUTHWEST...OR VARIABLE DRAINAGE FLOW IS EXPECTED THROUGH TONIGHT...THEN INCREASING SW-W UP TO 10 KTS ON MONDAY. OUTLOOK... MON...VFR. OCNL SHRA. CHC TSRA IN PM. TUE...VFR. CHC SHRA/TSRA PM. LOCAL MVFR. WED...VFR. SHRA/TSRA LIKELY. CHC MVFR. THU...VFR. FRI...VFR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...DJN NEAR TERM...DJN SHORT TERM... LONG TERM...JAB AVIATION...JAB
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
138 PM EDT SUN AUG 25 2013 .SYNOPSIS... AN APPROACHING FRONTAL SYSTEM WILL BRING A SCATTERED SHOWERS AND THUNDERSTORMS LATE TONIGHT AND MONDAY. DRY WEATHER IS FORECAST FOR TUESDAY...BUT MORE SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE TUESDAY NIGHT AND WEDNESDAY AS ANOTHER COLD FRONT MOVES THROUGH THE REGION. AFTER THIS FRONT PASSES BY...FAIR WEATHER IS EXPECTED FOR THURSDAY AND FRIDAY. && .NEAR TERM /THROUGH MONDAY/... VISIBLE SATL IMAGERY SHOWS SCT CUMULUS FORMING WITH INSOLATION. SOME CIRRUS FROM AN UPSTREAM MCS OVER NRN AND CNTRL ONTARIO AND THE UPPER LAKES WILL STREAM SOUTHEASTWARD FOR THE REST OF THE AFTERNOON....THUS SKIES WILL BE PS TO MS. CANADIAN RADAR LOOP SHOWS AN MCS WITH SHOWERS AND THUNDERSTORMS TRACKING SEWRD ACRS GEORGIAN BAY AND TWD SERN ONTARIO INTO WRN QUEBEC. CONVECTION ALLOWING MESOSCALE MODELS ...WRF-NMM, WRF-ARW AND HRRR ALL SHOW THE SRN EDGE OF THE PRECIPITATION SHIELD WITH THIS MCS SKIRTING ACRS NRN AND ERN NY TONIGHT WITH ELEVATED INSTABILITY REMAINING ON THE BACK EDGE OF THE MCS AS IT WORKS SEWRD. THE MAIN QUESTION IS TIMING. LATEST WRF-NMM AND WRF-ARW BOTH HAVE SHRA AND TSRA ARRIVING AFTER 6Z...MAINLY 9-12Z ACRS NC NY SEWRD TO THE CATSKILLS. THE HRRR ON THE OTHER HAND HAS THE PRECIP SHIELD AND SOME TSRA ARRIVING MUCH ERLR...SPREADING FROM NC NY SOUTHWARD TO THE CATSKILLS AND EVEN NE PA BETWEEN 1Z AND 6Z ABT 4-6 HOURS SOONER. TTHE NAM...GFS AND CANADIAN ALL BRING SOME LIGHT PRECIP INTO THESE AREAS LATE TONIGHT WITH THE RUC A LITTLE FASTER ON THE ARRIVAL OF THE PRECIP. THUS THE HRRR AND THE RUC TO A LESSER EXTENT AERE ON AN ISLAND BY THEMSELVES. HOWEVER...JUDGING BY LATEST RADAR LOOP IT LOOKS LIKE THE HRRR HAS THE BEST HANDLE...BUT THIS IS A MAJOR DEPARTURE FROM ERLR FCSTS AND ALL OTHER MODEL GUIDC AND SOUNDINGS INDICATE THAT IT IS VERY DRY BELOW 10000 FEET. SO FOR NOW WILL HAVE CHC POPS NRN AND ERN CWA INCREASING AFTR 6Z...BUT WILL RE-EVALUATE AND MAY HAVE TO BUMP UP POPS ERLR. I WUD LIKE TO SEE RADAR TRENDS ON THE SRN EDGE OF THIS MCS AND IF THE PRECIP IS REACHING THE GRND NEXT COUPLE HOURS. FOR MONDAY...AN UPPER LEVEL WAVE WILL MOVE EASTWARD TWD NY AND PA IN THE NW UPPER LEVEL FLO PATTERN. CONVECTION ALLOWING MODELS...ESPECIALLY THE WRF-NMM, AND WRF-ARW AS WELL AS THE NAM AND HIGHER RES CANADIAN ALL INDICATE SOME POTENTIAL FOR TRAINING THUNDERSTORMS AS THE LL FLOW WILL BE W-NW AND FAIRLY ALIGNED WITH THE UPPER LEVEL FLO. BOTH THE CANADIAN AND NAM HAVE A WELL DEVELOPED JET ENTRANCE REGION CIRCULATION FOR OUR AREA WHEREAS THE ERLR EURO AND 12Z GFS REALLY DON/T. MODEL CAPES ARE AVERAGING ARND 1000 J/KG OR SO WITH MODEST SHEAR VALUES...GENERALLY 25 TO 30 KNOTS IN THE LOWEST 6 KM WITH MOST OF THE SHEAR ACTUALLY BETWEEN 0 AND 3 KM. I CAN EASILY SEE AN MCS EVOLVING OVER OUR REGION MON PM AND...IN ITS WAKE SOME TRAINING STORMS WITH LOCALLY HEAVY RAINS. FOR NOW...THINK LIKELY POPS ARE ON ORDER MON PM. THERE IS WAY TOO MUCH UNCERTAINTY AS TO HEAVY RAINFALL POTENTIAL. NAM AND CMC GIVE THE REGION A STRIPE OF 1-2 INCHES OF RAIN WHICH SHUDN/T BE MUCH OF A PROBLEM AT ALL. HOWEVER WILL ALERT FUTURE SHIFTS FOR POTENTIAL TO RAISE SITUATIONAL AWARENESS. AS FOR SEVERE POTENTIAL...THERE CUD BE SOME LOCALLY DAMAGING WINDS...BUT AT THIS POINT IT LOOKS LIKE THE CAPE AND SHEAR FALL SHORT OF WHAT WE WOULD EXPECT FOR AN OUTBREAK. SPC CONCURS IN THEIR DAY 2 OUTLOOK. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/... LINGERING SHRA/TSRA PSBL MON EVNG AS FNTL SYSTEM DEPARTS AND WEAK HI PRES BUILDS INTO THE RGN. NAM/GFS PROFILES BOTH SHOW FAIRLY SIG LOW LVL MSTR BEHIND THIS BNDRY PERSISTING INTO TUE MRNG...WHICH SHUD BURN OFF BY LATE MRNG LEAVING PS SKIES. THE NXT S/WV AND FNTL SYSTEM APRCHS TUE NGT. ALL MDLS SUGGEST MCS POTNL BUT THERE ARE SIG DIFFS W/RESPECT TO THE TRACK OF THE SFC LOW/MCS. GFS/NAM SUGGEST A MORE SWD TRACK OF THE LOW AND MCS...WHILE THE EURO/GEM INDICATE A MORE NRLY TRACK. NO DOUBT LATER FCSTS WILL BE TWEAKED AS WE GET CLOSER TO THE EVENT...SO FOR NOW WENT WITH MOS POPS (CHC) FOR THESE TIME PDS. && .LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/... 4 AM SUN UPDATE... NOT MUCH CHG TO THE PREV FCST...AS EC/GFS/WPC CONSENSUS STILL SHOWS AN EXPANSIVE SUBTROP UPR RIDGE TO BE THE MAIN WX INFLUENCE OVER MUCH OF THE CONUS THIS PD. ALTHOUGH THIS RIDGE IS INITIALLY CENTERED OVER THE MIDDLE OF THE COUNTRY AT MID- WEEK (START OF THE PD)...IT IS PROGGED TO SLOWLY EXPAND EWD WITH TIME BY NEXT WEEKEND. AS A RESULT...SEASONABLE TEMPS WED-FRI (HIGHS FROM THE MID 70S-LWR 80S) SHOULD WARM MORE SOLIDLY INTO THE 80S THEREAFTER. AS FOR THE DAILY SENSIBLE WX...A COLD FRNTL BNDRY IS STILL EXPECTED TO CROSS NY/PA FROM NW TO SE SOMETIME LTR WED OR EARLY THU...WITH SHWRS/TSTMS ALG AND AHD OF THIS FEATURE. AS THIS SYSTEM IS STILL SVRL DAYS AWAY...WE`LL CONTINUE TO ADVERTISE CHC POPS FOR NOW ON WED AND WED NGT...DECREASING WITH TIME BY THU. FROM FRI THROUGH NEXT WEEKEND...RAIN-FREE CONDS LOOK PROBABLE...WITH RIDGING BUILDING IN BOTH SFC AND ALOFT. PREV DISC... ECMWF AND GFS IN PRETTY GOOD AGREEMENT REGARDING A STRONG RIDGE BUILDING THROUGHOUT THE CENTRAL U.S. AND EVENTUALLY SPREADING ITS INFLUENCE EASTWARD. A TROF WILL EXTEND ACROSS THE GREAT LAKES TUESDAY NIGHT, WITH AN ASSOCIATED SFC CYCLONE AND COLD FRONT PROGGED TO PULL THROUGH NY/PA ON WEDNESDAY. CHANCE TO SCATTERED THUNDERSTORM COVERAGE IS FORECAST THROUGH WEDNESDAY. A DRY NORTHWEST FLOW WILL DEVELOP FOR THURSDAY AND FRIDAY, AS THE PLAINS RIDGE BUILDS THROUGH OHIO AND MICHIGAN. FAIR WEATHER AND MAINLY CLEAR SKIES ARE FORECAST FOR NY/PA. && .AVIATION /17Z SUNDAY THROUGH THURSDAY/... 12Z SUN UPDATE... ONGOING FOG AT KELM SHOULD BURN OFF BY ARND 14Z. OTHWS...VFR WILL CONTINUE TO PREVAIL. WE MAY SEE A FEW SHWRS IN THE VICINITY OF KRME/KSYR TWDS 10-12Z MON...BUT PROBABILITIES DON`T SEEM HIGH ENUF TO MAKE MENTION OF THIS IN THE TERMINALS ATTM. OUTLOOK... MON THROUGH WED...ALTHOUGH VFR CONDS ARE PROBABLE THE MAJORITY OF THE TIME...PERIODIC SHWRS/TSTMS ARE PSBL (MOST LIKELY DURG THE AFTN/EVE HRS). ANY SUCH SHWR/TSTM COULD BRIEFLY PRODUCE RESTRICTIVE CONDS. BY THU...GENERALLY VFR CONDS ARE EXPECTED. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...DJN NEAR TERM...DJN SHORT TERM... LONG TERM...DJP/MLJ AVIATION...KAH/MLJ
AREA FORECAST DISCUSSION
NWS BISMARCK ND
521 PM CDT SUN AUG 25 2013 .UPDATE... ISSUED AT 520 PM CDT SUN AUG 25 2013 QUICK UPDATE TO INCREASE AND EXPAND POPS ACROSS WESTERN AND CENTRAL NORTH DAKOTA FOR THE REMAINDER OF THE EVENING AND OVERNIGHT. SURFACE BASED CONVECTION HAS BEEN INCREASING ACROSS SOUTHWEST NORTH DAKOTA AND NORTHWEST SOUTH DAKOTA SINCE 2130 UTC GIVEN THE LOSS OF CAPPING AND INCREASING UPPER LEVEL FORCING WITH THE SHORTWAVE ENTERING WESTERN NORTH DAKOTA EVIDENT ON THE LATEST WATER VAPOR IMAGERY. DEEP LAYER SHEAR ON THE ORDER OF 30-35 KTS SUPPORTS THE POTENTIAL FOR PERHAPS A SUPERCELL OR TWO...WITH ML CAPE VALUES AROUND 1500 J/KG. WHILE HIGH FREEZING LEVELS LIMIT THE HAIL THREAT...DOWNDRAFT CAPE VALUES NEAR 1400 J/KG SUGGEST A DAMAGING WIND THREAT WITH THE STRONGER STORMS. THE 18 UTC NAM AND 20 UTC HRRR ARE HANDLING THE CONVECTION WELL...WITH THE HRRR SUGGESTING THE CONVECTION WILL PROPAGATE INTO BISMARCK AND MANDAN LATER TONIGHT. && .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 317 PM CDT SUN AUG 25 2013 LATE SUNDAY AFTERNOON...SURFACE HIGH PRESSURE WAS ACROSS SOUTHERN MANITOBA. A WEAK COLD FRONT WAS SLIDING SOUTH ACROSS CENTRAL NORTH DAKOTA. ON SATELLITE...WATER VAPOR IMAGERY SHOWS A SHORTWAVE TROUGH MOVE THROUGH WYOMING INTO CENTRAL MONTANA. THIS FEATURE IS SUPPORTING CONVECTION ACROSS EASTERN MONTANA. SOME SHOWERS AND ISOLATED THUNDERSTORMS SHOULD ENTER WEST CENTRAL AND NORTHWEST NORTH DAKOTA LATE THIS AFTERNOON AND EVENING. THEN PROGRESSIVELY TRACKED THE SLIGHT CHANCE TO CHANCE OF THUNDERSTORMS INTO WESTERN NORTH DAKOTA OVERNIGHT AND INTO CENTRAL NORTH DAKOTA MONDAY. WITH THE BASIC RIDGE PATTERN IN PLACE OVER THE CENTRAL AND NORTHERN PLAINS...CONTINUED WARM TEMPERATURES EXPECTED ON MONDAY...HOWEVER WITH COLD FRONT BRINGING A SLIGHT RELIEF WITH HIGHS IN THE UPPER 80S NORTH TO LOWER 90S SOUTH ON MONDAY. .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) ISSUED AT 317 PM CDT SUN AUG 25 2013 MAIN FORECAST ISSUES IN THE LONG TERM WILL BE DAYTIME HIGH TEMPERATURES AND PERIODIC THUNDERSTORM CHANCES. THERE IS A CONTINUED GOOD AGREEMENT AMONG BOTH THE ENSEMBLE AND DETERMINISTIC MODELS IN THE MEAN UPPER LEVEL FLOW WHICH FEATURES A STRONG RIDGE OVER THE CENTRAL U.S. THAT RETROGRADES FROM THE MISSOURI VALLEY WEST INTO THE SOUTHERN PLAINS THROUGH THE PERIOD. NORTH DAKOTA WILL REMAIN NEAR THE APEX OF THE RIDGE THROUGH THE LONG TERM FORECAST PERIOD...WHICH WILL CONTINUE TO INDICATE ABOVE AVERAGE DAYTIME HIGH TEMPERATURES. SOUTHERN PORTIONS OF THE CWA COULD FLIRT WITH HEAT ADVISORY CRITERIA LATER IN THE WEEK. IN ADDITION...ALMOST DAILY THUNDERSTORM CHANCES CAN BE EXPECTED WITH HIGH CAPES EVERY DAY BUT A STRONG CAP LIMITING CONVECTION. THE DETERMINISTIC MODELS CONTINUE TO ADVERTISE A FEW...MORE SIGNIFICANT...WAVES WORKING THROUGH THE MEAN RIDGE AND BRINGING BETTER PRECIPITATION CHANCES. ON MONDAY AND INTO MONDAY NIGHT THE ECMWF/GEM APPEAR STRONGER WITH A WAVE MOVING INTO NORTH DAKOTA AND BRING QPF ACROSS THE NORTH. THE SOUTH MAY REMAIN CAPPED UNDER WARM MID LEVEL TEMPERATURES. WAVES CONTINUE TO WORK THROUGH THE MEAN RIDGE ON WEDNESDAY THROUGH SATURDAY BUT TIMING AND PLACEMENT DIFFERENCES CONTINUE BETWEEN MODELS AND MODEL RUNS. THEREFORE WILL CONTINUE TO UTILIZE A BLENDED SOLUTION FOR PRECIPITATION. THIS WILL MEAN BETTER CHANCES WEDNESDAY THROUGH THURSDAY AFTERNOON...THEN CHANCES ARE ON AND OFF FRIDAY NIGHT THROUGH SUNDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 310 PM CDT SUN AUG 25 2013 AT 3 PM CDT...A COLD FRONT EXTENDED ACROSS CENTRAL NORTH DAKOTA. THE FRONT IS FORECAST TO SLIDE SOUTH TONIGHT. A SHORTWAVE TROUGH IS IDENTIFIED ON SATELLITE MOVING INTO EASTERN MONTANA. WIDELY SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL MOVE INTO WESTERN NORTH DAKOTA IMPACTING KISN/KDIK THIS EVENING. HOWEVER...TOO WIDELY SCATTERED TO MENTION TSRA AT THIS TIME. AS THE SHORTWAVE MOVES THROUGH WESTERN NORTH DAKOTA TONIGHT AND MONDAY WILL SEE PROGRESSIVE EASTWARD CHANCE OF THUNDERSTORMS. AGAIN...TO UNCERTAIN AT THIS TIME...BUT WILL USE VCTS TO INDICATE GENERAL SENSE OF THUNDERSTORMS. VFR EXPECTED AT ALL TAF SITES. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...AYD SHORT TERM...WAA LONG TERM...JV AVIATION...WAA
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1209 PM CDT SUN AUG 25 2013 .UPDATE... ISSUED AT 1155 AM CDT SUN AUG 25 2013 AT NOON CDT...A WEAK FRONTAL BOUNDARY ACROSS NORTHERN NORTH DAKOTA IS FORECAST TO SLIDE SLOWLY SOUTH. LITTLE WEATHER WITH THIS FEATURE AS IT LIES BENEATH AN H500 RIDGE. WATER VAPOR IMAGERY IS TRACKING A SHORTWAVE MOVING NORTHEAST UP THE WESTERN PORTION OF THE RIDGE WHICH SHOULD SUPPORT SOME CONVECTION ACROSS WESTERN NORTH DAKOTA LATER TONIGHT. FOR THIS UPDATE...REMOVED THE SLIGHT CHANCE FOR THUNDERSTORMS SOUTHEAST. WILL LEAVE TEMPS/WINDS AS IS. UPDATE ISSUED AT 1000 AM CDT SUN AUG 25 2013 WEAK HIGH PRESSURE PATTERN OVER THE STATE THIS MORNING WITH A WEAK TROUGH OF LOW PRESSURE LINGERING ACROSS SOUTH CENTRAL AND SOUTHEAST NORTH DAKOTA. THIS COULD BE THE FOCUS FOR AN ISOLATED THUNDERSTORM THIS MORNING. WILL RE EVALUATE THE POTENTIAL FOR THE AFTERNOON...FOR NOW LEFT A SLIGHT CHANCE THUNDERSTORMS SOUTHEAST THIS MORNING WHERE HRRR MODEL GENERATES ISOLATED CONVECTION. ARE OF CLOUDS IN CENTRAL/EASTERN MONTANA APPEAR TO BE ASSOCIATED WITH A SHORT WAVE CENTERED IN WESTERN WYOMING MOVING NORTHEAST. THE RIDGE MAY PREVENT THE CLOUDS AND SHOWERS/THUNDERSTORMS FROM MAKING MUCH EASTWARD ADVANCEMENT INTO WESTERN NORTH DAKOTA THIS AFTERNOON... ALTHOUGH NEW NAM GENERATES SOME THUNDERSTORMS AFTER 3 PM. DON`T HAVE ENOUGH CONFIDENCE TO MOVE UP THE TIME TABLE FORM THIS EVENING INTO THE IS AFTERNOON. UPDATE ISSUED AT 644 AM CDT SUN AUG 25 2013 MAINLY CLEAR SKIES ACROSS WESTERN AND CENTRAL NORTH DAKOTA THIS MORNING. HIGH PRESSURE OVER THE WEST WITH DRIER AIR WORKING INTO THE AREA ALLOWED TEMPERATURES TO FALL INTO THE LOWER TO MIDDLE 50S. MEANWHILE A LOW PRESSURE TROUGH REMAINS FROM CENTRAL SOUTH DAKOTA INTO EAST CENTRAL NORTH DAKOTA WITH MUCH HIGHER HUMIDITIES. TEMPERATURES HERE HAVE ONLY FALLEN INTO THE UPPER 60S AND LOWER 70S. NO SIGNIFICANT CHANGES TO THE FORECAST THIS UPDATE. DID KEEP A SLIGHT CHANCE OF THUNDER OVER THE SOUTHEAST NEAR THE WEAK SURFACE TROUGH. LATEST 06 UTC NAM IS INDICATING LIGHT QPF ENTERING INTO THE WEST LATER THIS AFTERNOON. WILL LEAVE THIS OUT OF THE FORECAST FOR NOW BUT WILL LET THE DAY SHIFT MONITOR. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 303 AM CDT SUN AUG 25 2013 MAIN HIGHLIGHT IN THE SHORT TERM WILL BE ANOTHER HOT DAY WITH HIGHS WELL INTO THE 90S...HOWEVER THUNDERSTORMS WILL BE CONFINED TO FAR SOUTH CENTRAL NORTH DAKOTA AND THE SOUTHERN JAMES RIVER VALLEY. EARLY THIS MORNING...THE LATEST LOCAL RADAR SHOWS A LINE OF SHOWERS AND THUNDERSTORMS INITIATING ALONG A FRONTAL BOUNDARY/LOW CONVERGENCE ZONE...STRETCHING FROM CORSON COUNTY IN SOUTH DAKOTA NORTHEAST BETWEEN BURLEIGH AND EMMONS COUNTY AND INTO STUTSMAN COUNTY. WATER VAPOR INDICATIVE OF A SHORTWAVE MOVING THROUGH CENTRAL NORTH DAKOTA EARLY THIS MORNING PROVIDING THE LIFT NEEDED TO SUSTAIN AND REDEVELOP THE PRECIPITATION. A COUPLE OF THE THUNDERSTORMS HAVE COME CLOSE TO SEVERE CRITERIA...AND WILL CONTINUE TO MONITOR. FOR TODAY...UPPER LEVEL RIDGING CENTERED OVER CENTRAL KANSAS COMBINED WITH AN UPPER TROUGH ALONG THE WEST COAST...WILL MAINTAIN A SOUTHWEST FLOW INTO NORTH DAKOTA. A COUPLE OF SHORTWAVES ARE FORECAST TO SLIDE ACROSS THE NORTHERN BORDER WITH LITTLE OR NO AFFECT IN TERMS OF PRECIPITATION. THE AFOREMENTIONED FRONTAL BOUNDARY IS FORECAST TO SHIFT A BIT FURTHER SOUTH TODAY...INTO NORTHERN SOUTH DAKOTA. HOWEVER A SHORTWAVE MOVING OUT FROM COLORADO IS FORECAST TO MOVE INTO CENTRAL SOUTH DAKOTA THIS AFTERNOON. THIS SHOULD LEAD TO ISOLATED THUNDERSTORMS IN OUR SOUTHEAST ZONES CLOSEST TO THE FRONT. ELSEWHERE EXPECT MOSTLY SUNNY...DRY..AND HOT CONDITIONS WITH HIGHS 90F TO 98F. HEAT INDICES ARE FORECAST IN THE MID TO UPPER 90S IN OUR SOUTH CENTRAL ZONES AND WILL CONTINUE TO MENTION THIS IN THE HAZARDOUS WEATHER OUTLOOK. FOR SUNDAY NIGHT...LEE SIDE TROUGH DEVELOPS IN SOUTHEAST MONTANA AS A COUPLE OF SHORTWAVES ARRIVE VIA THE SOUTHWEST FLOW INTO WESTERN NORTH DAKOTA. HAVE MENTIONED ISOLATED THUNDERSTORMS WEST SUNDAY NIGHT WITH DRY CONDITIONS CENTRAL. LOWS WILL AGAIN BE IN THE 60S. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 303 AM CDT SUN AUG 25 2013 MAIN FORECAST ISSUES IN THE LONG TERM WILL BE DAYTIME HIGH TEMPERATURES AND PERIODIC THUNDERSTORM CHANCES. THERE IS A CONTINUED GOOD AGREEMENT AMONG BOTH THE ENSEMBLE AND DETERMINISTIC MODELS IN THE MEAN UPPER LEVEL FLOW WHICH FEATURES A STRONG RIDGE OVER THE CENTRAL U.S. THAT RETROGRADES FROM THE MISSOURI VALLEY WEST INTO THE SOUTHERN PLAINS THROUGH THE PERIOD. NORTH DAKOTA WILL REMAIN NEAR THE APEX OF THE RIDGE THROUGH THE WHICH WILL CONTINUE TO INDICATE VERY WARM DAYTIME HIGH TEMPERATURES. SOUTHERN PORTIONS OF THE CWA COULD FLIRT WITH HEAT ADVISORY CRITERIA ON MONDAY AND AGAIN LATER IN THE WEEK. IN ADDITION... ALMOST DAILY THUNDERSTORM CHANCES CAN BE EXPECTED WITH HIGH CAPES EVERY DAY BUT A STRONG CAP LIMITING CONVECTION. THE DETERMINISTIC MODELS CONTINUE TO ADVERTISE A FEW...MORE SIGNIFICANT...WAVES WORKING THROUGH THE MEAN RIDGE AND BRINGING BETTER PRECIPITATION CHANCES. ON MONDAY THE ECMWF/GEM APPEAR STRONGER WITH A WAVE MOVING INTO NORTH DAKOTA AND BRING QPF ACROSS THE NORTH. THE SOUTH WILL LIKELY REMAIN CAPPED UNDER WARM MID LEVEL TEMPERATURES. THE GFS IS STRONGER WITH THE RIDGING OVER THE AREA AND KEEPS PRECIPITATION MAINLY NORTH OF THE BORDER. WAVES CONTINUE TO WORK THROUGH THE MEAN RIDGE ON WEDNESDAY THROUGH FRIDAY BUT TIMING AND PLACEMENT DIFFERENCES INCREASE WITH LESS CONSENSUS BETWEEN THE MODELS EXISTS THAN THE MODEL RUNS FROM 24 HOURS AGO. THEREFORE WILL CONTINUE TO UTILIZE A BLENDED SOLUTION FOR PRECIPITATION. MODELS DO INDICATE AT LEAST A TEMPORARY BREAKDOWN OF THE UPPER RIDGE LATE IN THE PERIOD WITH THE ECMWF A GOOD 18 TO 24 HOURS QUICKER TO BRING PRECIPITATION CHANCES AND COOLER TEMPERATURES TO THE AREA. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 1155 AM CDT SUN AUG 25 2013 AT NOON CDT...A REGION OF HIGH PRESSURE ACROSS SOUTHERN CANADA AND NORTHERN NORTH DAKOTA WILL BRING VFR CONDITIONS TO THE REGION THROUGH THE 18Z TAF PERIOD. A WEAK FRONTAL BOUNDARY WILL MOVE TO SOUTHEAST MONTANA AND SOUTHERN NORTH DAKOTA SUNDAY NIGHT. A SHORTWAVE TROUGH ACROSS WYOMING INTO SOUTHERN MONTANA WILL BE THE FEATURES THAT FOCUS SCATTERED THUNDERSTORMS ACROSS WESTERN NORTH DAKOTA LATE TONIGHT INTO MONDAY MORNING WEST. THIS WILL IMPACT KDIK-KBIS-KMOT-KISN AFTER 06Z. WILL HANDLE WITH VCTS AS THREAT FAIRLY ISOLATED. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...WAA SHORT TERM...KS LONG TERM...TWH AVIATION...WAA
AREA FORECAST DISCUSSION
NWS TULSA OK
1211 PM CDT SUN AUG 25 2013 .DISCUSSION... THE 18Z TAF DISCUSSION IS INCLUDED BELOW. && .AVIATION... CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM. VFR CONDITIONS WILL PREVAIL BENEATH A MID AND UPPER LEVEL RIDGE OF HIGH PRESSURE. THE ONLY EXCEPTION WILL BE SOME LIGHT MVFR FOG AT KBVO...KRVS AND THE W/NW AR TAF SITES AROUND 12Z IN THE MORNING. SHRA/TSRA CHANCES ARE TOO LOW TO MENTION IN THE TAFS. LACY && .PREV DISCUSSION... /ISSUED 904 AM CDT SUN AUG 25 2013/ DISCUSSION... ANOTHER HOT AND HUMID DAY IS IN STORE FOR EASTERN OKLAHOMA AND NORTHWEST ARKANSAS WITH MID/UPPER RIDGING IN CONTROL. 12Z UPPER AIR DATA INDICATES 500MB HEIGHTS ARE RISING AND SOME 700MB MOISTURE REMAINS AT LITTLE ROCK...SHREVEPORT AND FORT WORTH. THIS WOULD SUGGEST THE BEST POTENTIAL FOR ISOLATED AFTERNOON SHOWERS/STORMS WILL BE OVER THE HIGH TERRAIN OF SOUTHEAST OKLAHOMA AND/OR WEST CENTRAL ARKANSAS AND DOWN NEAR THE RED RIVER. COVERAGE OF PRECIP YESTERDAY WAS VERY LOW...AND WITH THE RISING UPPER HEIGHTS THAT WILL LIKELY NOT CHANGE TODAY. THE LATEST HRRR SHOWS HINTS OF ISOLATED DEVELOPMENT DOWN IN THAT REGION. WILL ELECT TO CARRY SILENT 10 POPS THERE...AND WILL MONITOR THE CU FIELD LATER TODAY TO SEE IF AN INCREASE IS WARRANTED IN SPOTS. LACY PREV DISCUSSION... /ISSUED 320 AM CDT SUN AUG 25 2013/ DISCUSSION... A LARGE UPPER RIDGE WILL REMAIN PARKED OVER THE AREA THROUGH THE ENTIRE FORECAST PERIOD. THE GFS IS QUICKER THAN THE ECMWF TO BEGIN TO BREAK DOWN THE RIDGE NEXT WEEKEND INTO THE FIRST WEEK OF SEPTEMBER WHICH IS A REVERSAL FROM MODEL RUNS A COUPLE DAYS AGO. IN THE MEANTIME...HOT WEATHER WITH VERY LITTLE CHANCE OF RAIN WILL PREVAIL. TEMPERATURES WILL SLOWLY INCH UP LATER THIS WEEK...LIKELY PEAKING ON FRIDAY OR SATURDAY. STAYED CLOSE TO GUIDANCE TEMPERATURES THE NEXT FEW DAYS. && .PRELIMINARY POINT TEMPS/POPS... TUL 94 74 94 74 / 0 0 0 0 FSM 94 73 94 73 / 10 0 0 0 MLC 94 73 95 73 / 10 10 10 0 BVO 94 69 94 69 / 0 0 0 0 FYV 91 67 90 67 / 10 0 0 0 BYV 91 69 90 69 / 0 0 0 0 MKO 94 71 93 71 / 0 0 0 0 MIO 91 71 93 71 / 0 0 0 0 F10 94 73 93 73 / 0 0 0 0 HHW 96 72 96 72 / 10 10 10 0 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...NONE. AR...NONE. && $$ AVIATION...30
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
419 PM EDT SUN AUG 25 2013 .SYNOPSIS... DRIER HIGH PRESSURE WILL PERSIST THROUGH MIDWEEK BEFORE AN UPPER LEVEL DISTURBANCE AND AN ASSOCIATED SURFACE COLD FRONT MOVE THROUGH THE REGION ON THURSDAY. THIS WILL BRING THE GREATEST CHANCES FOR SHOWERS AND THUNDERSTORMS FOR THE WEEK. WEAK HIGH PRESSURE WILL RETURN IN THE FRONTS WAKE FOR THE START OF NEXT WEEKEND. && .NEAR TERM /THROUGH MONDAY/... 4 PM UPDATE...LITTLE CHANGE EXCEPT TO TOUCH UP SKY...TEMPS AND DEWPTS FROM LATEST OBS. LATEST RAP DOES PRODUCE SOME LIGHT PRECIP THIS AFTN IN THE SMOKIES BUT SATELLITE TRENDS SUGGEST THE SCATTERED CLOUD COVER THERE IS TOO SHALLOW FOR PRECIP. WILL HOLD ON TO DRY FCST. AS OF 140 PM EDT SUNDAY...THE PATTERN WILL TRANSITION FROM ONE OF COLD AIR DAMMING...WITH A FAIRLY TIGHT SFC PRESSURE GRADIENT AND MODERATE LLVL ADVECTION OF DRY AND COOL AIR...TO ONE WITH A BROAD RIDGE OF HIGH PRESSURE COVERING THE ENTIRE REGION. THIS WILL SHUT OFF THE COLD ADVECTION...RESULTING IN MODERATING TEMPERATURES AND NEARLY CALM WINDS TONIGHT AND MONDAY. THE DEWPOINTS SHOULD STILL REMAIN LOW WITH SUBSIDENCE ACROSS THE SE STATES. THERE WILL BE SOME UPSLOPE INDUCED STRATO-CU MUCH OF THE NIGHT ALONG THE BLUE RIDGE. TOMORROW WE SHOULD SEE A WIDESPREAD CU FIELD DEVELOP ACROSS THE REGION DURING THE LATE MORNING AND AFTERNOON HOURS. TONIGHT/S FORECAST LOW TEMPERATURE OF 58 DEGREES AT CHARLOTTE...IF IT VERIFIES...WILL BE THE COOLEST READING SINCE JUNE 15TH. AND WHILE CHARLOTTE DID SEE A COUPLE READINGS IN THE 50S LAST AUGUST...THEY HADN/T SEE READINGS IN THE 50S DURING THIS MONTH SINCE 2004 BEFORE THAT. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/... AT 150 PM EDT SUNDAY...AN UPPER RIDGE WILL BE CENTERED OVER THE MIDDLE OF THE NATION MONDAY EVENING...WHILE AN UPPER TROUGH AXIS REMAINS OFF THE EAST COAST. THE UPPER TROUGH AXIS RETROGRESSES CLOSER TO THE COAST BY WEDNESDAY....SUCH THAT HEIGHTS FALL ALONG HE EASTERN SEABOARD. A SHORTWAVE TROUGH WILL DROP INTO THE ATLANTIC TROUGH MONDAY NIGHT...CROSSING THE NORTHEAST USA. ANOTHER...WEAKER SHORTWAVE WILL FOLLOW SUIT LATE TUESDAY AND CROSS THE MID ATLANTIC REGION...AND A THIRD SYSTEM CROSS THE CAROLINAS ON WEDNESDAY. WEAKENING HIGH PRESSURE WILL BE IN PLACE OVER THE CAROLINAS AND GA ON MONDAY NIGHT. MODEL TIME HEIGHTS SHOW VERY DRY AIR BETWEEN 850 MB AND 300 MB...WITH LIMITED LOW LEVEL MOISTURE. ON TUESDAY A SURFACE TROUGH IS EXPECTED TO FORM IN THE LEE OF THE MOUNTAINS AS THE SURFACE HIGH MOVES WEST ACROSS THE GULF STATES...WHILE BOTH LOW AND MID LEVEL MOISTURE INCREASE FROM THE NORTH AHEAD OF A COLD FRONT APPROACHING THE OH RIVER VALLEY. THE LEE TROUGH PERSISTS INTO WEDNESDAY...WHILE THE MODELS CONTINUE TO SHOW A RELATIVE DRY LAYER...ALBEIT SLOWLY MOISTENING...BETWEEN AROUND 600 MB AND 800 MB. PRECIPITATION IS NOT EXPECTED ON MONDAY NIGHT THROUGH TUESDAY NIGHT WITH INITIALLY DRY MID LEVELS...AND PRONOUNCED SUBSIDENCE INVERSION. PRECIPITATION CHANCES INCREASE ON WEDNESDAY WITH INCREASING MOISTURE AND INSTABILITY...AND COOLING ALOFT...BUT WILL STILL REMAIN IN THE CHANCE CATEGORY. TEMPERATURES WILL WARM FROM SLIGHTLY BELOW NORMAL MONDAY NIGHT...TO NEAR NORMAL FROM TUESDAY THROUGH WEDNESDAY...AS THE AIR MASS MODIFIES...AND HIGH PRESSURE MOVES OFF TO THE WEST...INTRODUCING A LIGHT WESTERLY DOWNSLOPE FLOW COMPONENT. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... AS OF 130 PM EDT SUNDAY...THE MEDIUM RANGE PICKS UP AT 00Z ON THURSDAY WITH THE LARGE UPPER RIDGE CENTERED OVER THE CENTRAL CONUS AND NORTHERN STREAM UPPER TROFFING OVER SOUTHEASTERN CANADA. THE UPPER RIDGE IS EXPECTED TO REMAIN LARGELY IN PLACE IF NOT SLIDE A BIT WESTWARD OVER THE NEXT FEW DAYS AND THEN FLATTEN OVER THE WEEKEND. THIS WILL RESULT IN MINOR HEIGHT FALLS AND A FEW WEAK SHORTWAVES MOVING OVER THE FCST ARE ON THURS AND FRI. AT THE SFC...A TRAILING COLD FRONT WILL MOVE INTO THE CWFA EARLY IN THE DAY AND BRING A PLUME OF DEEPER MOISTURE WITH IT. MODELS INDICATE THAT THE FRONT SHOULD BE MOVING OFF THE SE COAST BY LATE THURS/EARLY FRI WITH ANOTHER CANADIAN SFC HIGH BRINGING WEAK NLY LOW LVL FLOW IN THE FRONTS WAKE. OVER THE WEEKEND...AS THE HIGH MOVES NE OF THE REGION...WINDS WILL LIKELY BECOME NEAR CALM AND THEN EVENTUALLY SLY AS THE BERMUDA HIGH TRIES TO REGAIN ITS INFLUENCE. POPS AND QPF WERE REDUCED A BIT ON THURS AS THE LATEST MODEL RUNS ARE SUGGESTING A DRIER OVERALL FROPA. OTHERWISE...I STILL CARRY DIURNAL CHANCE TO SLIGHT CHANCE POPS FOR FRI AND SLIGHT CHANCE FOR SAT AND SUN. I BUMPED UP HIGH TEMPS A DEGREE OR 2 FOR THURS AND FRI WITH VALUES NOW AROUND CLIMO. VALUES WILL LIKELY DROP A FEW DEGREES FOR SAT AND SUN WITH LOWER THICKNESSES ANTICIPATED. && .AVIATION /20Z SUNDAY THROUGH FRIDAY/... AT KCLT /21Z UPDATE/...A DEEP LAYER RIDGE OF HIGH PRESSURE WILL REMAIN OVER THE REGION THROUGH THE VALID PERIOD OF THE TAF. THE GRADIENT WILL WEAKEN AS THE CENTER OF THE RIDGE MOVES OVERHEAD...RESULTING IN A LONG PERIOD OF CALM WINDS TONIGHT AND MONDAY MORNING. WINDS THIS AFTN SHOULD REMAIN OUT OF THE NE AT 5-8KTS...WITH A FEW GUSTS TO 10-15 KT PER TDWR WINDS JUST OFF THE SFC. SCT TO BKN CU IN THE 4-6KFT RANGE SHOULD PERSIST UNTIL AROUND 6 PM AT WHICH TIME THEY SHOULD DISSIPATE. ELSEWHERE...THE WEATHER PATTERN IS THE SAME AS AT KCLT WITH SIMILAR CONDITIONS AT THE OTHER AIRFIELDS. ONE POSSIBLE EXCEPTION IS AT KAVL. THEY SHOULD FALL UNDER THEIR CROSSOVER TEMPERATURE LATER TONIGHT. CERTAINLY PARTS OF THE FRENCH BROAD VALLEY WILL SEE FOG...BUT IT/S NEVER AN EASY CALL AT KAVL. I LIKED THE MID SHIFT/S 2SM AND SCT005 SO I RETAINED THAT IN THE FORECAST. OUTLOOK...A DRY PATTERN IS EXPECTED THROUGH TUESDAY AS HIGH PRESSURE BUILDS IN FROM THE NORTH AND PERSISTS. MOISTURE WILL START TO RETURN AHEAD OF A FRONT APPROACHING FROM THE NW DURING MID AND LATE WEEK. CONFIDENCE TABLE... 20-02Z 02-08Z 08-14Z 14-20Z KCLT HIGH 100% HIGH 100% HIGH 100% HIGH 100% KGSP HIGH 100% HIGH 100% HIGH 100% HIGH 100% KAVL HIGH 100% HIGH 100% LOW 56% HIGH 86% KHKY HIGH 100% HIGH 100% HIGH 100% HIGH 100% KGMU HIGH 100% HIGH 100% HIGH 100% HIGH 100% KAND HIGH 100% HIGH 100% HIGH 100% HIGH 100% THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE) WWW.WEATHER.GOV/GSP/AVIATION_TABLES && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...JPT NEAR TERM...MCAVOY/WIMBERLEY SHORT TERM...JAT LONG TERM...JPT AVIATION...MCAVOY/WIMBERLEY
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
310 PM CDT SUN AUG 25 2013 .DISCUSSION... NORTHWEST GULF OF MEXICO DEEP TROPICAL MOISTURE CONTINUES TO SPREAD SLOWLY WESTWARD INTO THE TEXAS COAST AS UPPER LEVEL RIDGING STRENGTHENS TO OUR NORTH. AS ANTICIPATED...ACTIVITY OVER THE GULF WATERS IS WEAKENING/DISSIPATING THIS AFTERNOON WHILE INLAND`S STRONGEST STORMS REMAIN GENERALLY CONFINED TO NEAR AND SOUTH OF INTERSTATE 10. PREVIOUS FORECASTS FROM THE LAST FEW DAYS THAT HAVE BEEN CALLING FOR UP TO AN INCH OR TWO OF RAIN FROM SUNDAY THROUGH TUESDAY WITH THE GREATEST CONCENTRATION ACROSS COASTAL COUNTIES AND ESPECIALLY OFFSHORE STILL LOOKS ON TRACK WITH THE NEXT SET OF STORMS EXPECTED TO DEVELOP LATER THIS EVENING AND ON THROUGH THE OVERNIGHT HOURS NEAR THE COAST AND JUST OFFSHORE. ACTIVITY SHOULD WORK ITS WAY INLAND DURING THE DAY TOMORROW...BUT THE GREATEST RAINFALL TOTALS ARE STILL ANTICIPATED TO BE NEAR THE COAST AND OFFSHORE. ANOTHER NOT SO HOT LATE AUGUST DAY IS EXPECTED UNDER ABUNDANT CLOUD COVER ON MONDAY. TUESDAY SHOULD BE OUR LAST CHANCE OF RAIN FOR THE WEEK AS THIS SYSTEM WORKS ITS WAY TO OUR WEST AND NORTHWEST AND UPPER LEVEL RIDGING AND ASSOCIATED SUBSIDENCE BUILDS ACROSS SOUTHEAST TEXAS. THIS PATTERN CHANGE TRANSLATES TO BACK TO NEAR NORMAL LATE AUGUST TEMPERATURES FOR THE ENTIRE AREA. 42 && .MARINE... SHOWERS AND THUNDERSTORMS HAVE BEEN ONGOING ALMOST ALL DAY TODAY OVER THE WATERS. THIS IS IN RESPONSE TO A WEAK TROPICAL WAVE WITH ITS AXIS LOCATED JUST SOUTH OF THE LAKE CHARLES AREA. WINDS HAVE BEEN AROUND SCEC CRITERIA FOR THE NEARSHORE WATERS WHILE BELOW CRITERIA PAST 20 NM. THE WAVE AXIS WILL CONTINUE TO NUDGE WESTWARD TONIGHT AS A SHORTWAVE AT 500 MB APPROACHES. SHOWERS AND THUNDERSTORMS WILL BE LIKELY MONDAY AND THEN BEGIN TO WANE EARLY TUESDAY AS THE WAVE AXIS MOVES AWAY. 23 && .PREV DISCUSSION... /ISSUED 1251 PM CDT SUN AUG 25 2013/ DISCUSSION... SEE AVIATION FOR 18Z TAF ISSUANCE. AVIATION... OVERVIEW...RAIN CONFINED TO THE COAST TODAY WITH MVFR DECKS ACROSS MOST OF SOUTHEAST TEXAS. ANOTHER BAND OF RAIN HAS DEVELOPED ALONG SOUTHERN LAKE CHARLES CWA BORDER AND IS MOVING TOWARDS THE WEST. A VORTICITY MAXIMUM ASSOCIATED WITH A SHORTWAVE WILL APPROACH THE COAST MONDAY. GFS/ NAM/ ECMWF HAVE THE FEATURE MOVING INLAND A TAD BEFORE 11Z WITH THE RAP BEING THE MOST PROGRESSIVE BRINGING THE SHORTWAVE IN AROUND 3Z MONDAY. KCLL/KUTS/KCXO...RAIN SHOULD FOR THE MOST PART REMAIN SOUTH OF THESE TAF SITES WITH MOSTLY BROKEN MVFR CLOUDS. LOOKS LIKE BULK OF RAIN MONDAY WILL ALSO BE SOUTH OF THESE TAF SITES. A SLIGHT DEVIATION IN THE TRACK OF THE SHORTWAVE COULD ALTER THE QPF FIELD THOUGH. WILL HAVE TO CLOSELY MONITOR SITUATION AND ADJUST ACCORDINGLY. KIAH/KHOU...CHANCE FOR SCATTERED SHOWERS TO AFFECT THE TERMINALS THIS AFTERNOON AS REDEVELOPMENT IS ALREADY OCCURRING OFF TO THE EAST. MOSTLY LIKELY THESE SITES WILL REMAIN IN MVFR CIGS FOR MOST OF TODAY. THERE MIGHT BE A SLIGHT BREAK THIS EVENING INTO EARLY MORNING BEFORE THE NEXT ROUND OF CONVECTION APPROACHES. TIMING OF THE SHORTWAVE IS AGAIN CRUCIAL HERE AS A SLIGHTLY MORE PROGRESSIVE MOVING SHORTWAVE WOULD FAVOR RAIN STARTING AROUND 6Z WITH THE GLOBAL MODELS BEING MUCH SLOWER WITH THE TIMING OF THE RAINFALL. KLBX/KSGR/KGLS...PRECIP IN ONGOING AT KGLS WITH PRECIP LIKELY AT KLBX AND KSGR. THESE SITES WILL BE THE FIRST LOCATIONS TO SEE THE RAINFALL MONDAY MORNING ALSO AS THE SHORTWAVE MOVES IN FROM THE EAST. 23 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 75 94 74 96 75 / 20 30 10 20 10 HOUSTON (IAH) 75 90 75 95 75 / 30 40 20 30 10 GALVESTON (GLS) 79 88 80 91 81 / 60 60 30 40 20 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL 10 PM CDT THIS EVENING FOR THE FOLLOWING ZONES: MATAGORDA BAY...WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL 20 NM TO 60 NM... WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM... WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM. && $$ DISCUSSION...42 AVIATION/MARINE...23
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
1251 PM CDT SUN AUG 25 2013 .DISCUSSION... SEE AVIATION FOR 18Z TAF ISSUANCE. && .AVIATION... OVERVIEW...RAIN CONFINED TO THE COAST TODAY WITH MVFR DECKS ACROSS MOST OF SOUTHEAST TEXAS. ANOTHER BAND OF RAIN HAS DEVELOPED ALONG SOUTHERN LAKE CHARLES CWA BORDER AND IS MOVING TOWARDS THE WEST. A VORTICITY MAXIMUM ASSOCIATED WITH A SHORTWAVE WILL APPROACH THE COAST MONDAY. GFS/ NAM/ ECMWF HAVE THE FEATURE MOVING INLAND A TAD BEFORE 11Z WITH THE RAP BEING THE MOST PROGRESSIVE BRINGING THE SHORTWAVE IN AROUND 3Z MONDAY. KCLL/KUTS/KCXO...RAIN SHOULD FOR THE MOST PART REMAIN SOUTH OF THESE TAF SITES WITH MOSTLY BROKEN MVFR CLOUDS. LOOKS LIKE BULK OF RAIN MONDAY WILL ALSO BE SOUTH OF THESE TAF SITES. A SLIGHT DEVIATION IN THE TRACK OF THE SHORTWAVE COULD ALTER THE QPF FIELD THOUGH. WILL HAVE TO CLOSELY MONITOR SITUATION AND ADJUST ACCORDINGLY. KIAH/KHOU...CHANCE FOR SCATTERED SHOWERS TO AFFECT THE TERMINALS THIS AFTERNOON AS REDEVELOPMENT IS ALREADY OCCURRING OFF TO THE EAST. MOSTLY LIKELY THESE SITES WILL REMAIN IN MVFR CIGS FOR MOST OF TODAY. THERE MIGHT BE A SLIGHT BREAK THIS EVENING INTO EARLY MORNING BEFORE THE NEXT ROUND OF CONVECTION APPROACHES. TIMING OF THE SHORTWAVE IS AGAIN CRUCIAL HERE AS A SLIGHTLY MORE PROGRESSIVE MOVING SHORTWAVE WOULD FAVOR RAIN STARTING AROUND 6Z WITH THE GLOBAL MODELS BEING MUCH SLOWER WITH THE TIMING OF THE RAINFALL. KLBX/KSGR/KGLS...PRECIP IN ONGOING AT KGLS WITH PRECIP LIKELY AT KLBX AND KSGR. THESE SITES WILL BE THE FIRST LOCATIONS TO SEE THE RAINFALL MONDAY MORNING ALSO AS THE SHORTWAVE MOVES IN FROM THE EAST. 23 && .PREV DISCUSSION... /ISSUED 1029 AM CDT SUN AUG 25 2013/ DISCUSSION... DEEP MOISTURE CONTINUES TO SLOWLY FILTER INTO SOUTHEAST TEXAS FROM THE EAST THIS MORNING IN ASSOCIATION WITH A NORTHWESTERN GULF OF MEXICO DISTURBANCE. PER WATER VAPOR SATELLITE LOOP... A MUCH DRIER AIR MASS IS MOVING INTO THE NORTHERN PORTIONS OF OUR AREA...AND THIS IS EXPECTED TO KEEP THE MAJORITY OF SPOTS GENERALLY ALONG AND NORTH OF INTERSTATE ON THE DRY SIDE TODAY. RECENT RADAR TRENDS HAVE ACTIVITY WEAKENING NEAR THE COAST AND OFFSHORE...SO HAVE MADE SOME DOWNWARD POP ADJUSTMENTS TO AREA FORECASTS FOR THE REST OF THE DAY. ALSO...SHAVED OFF SEVERAL DEGREES FROM THIS AFTERNOON`S HIGH TEMPERATURES BASED ON THE ANTICIPATED EXTRA CLOUD COVER. 42 PREV DISCUSSION... /ISSUED 419 AM CDT SUN AUG 25 2013/ DISCUSSION... ONGOING FCST HAS BEEN LEFT LARGELY UNCHANGED. DEEPER MOISTURE IS MOVING INTO THE UPPER TEXAS COASTAL WATERS AND COUNTIES FROM THE EAST. EXPECT PERIODS OF SHRA/TSRA ACROSS THE SRN PARTS OF THE REGION THRU THE DAY WITH BEST COVERAGE SOUTH OF I-10. DID KNOCK POPS DOWN ACROSS FAR NORTHERN COUNTIES WHERE COMPETITION FROM UPPER RIDGE IS MORE PRONOUNCED. WE`LL PROBABLY SEE A BREAK IN MOST PRECIP LATE IN THE AFTN AND EARLY THIS EVENING FOLLOWED BY WIDESPREAD REDEVELOPMENT OFFSHORE AND ALONG THE COAST TONIGHT AND MON MORNING. COVERAGE WILL THEN GRADUALLY EXPAND INLAND INTO THE SW HALF OF THE REGION DURING THE DAY. EXPECTING THE BEST COVERAGE IN THE COUNTIES SW/W OF THE METRO AREA (THAT NEED THE RAINFALL THE MOST). CHANCES OF RAINFALL WILL DIMINISH ON TUE/WED AS MOISTURE AXIS GRADUALLY PUSHES OUT OF THE REGION. BY LATE WED & THURS RAIN CHANCES WILL BE CLOSE TO NIL AS PW`S DROP AND UPPER RIDGE REALLY REESTABLISHES ITSELF OVERHEAD. TEMPS SHOULD CLIMB BACK INTO THE UPPER 90S TO NEAR 100 AT SOME LOCATIONS DURING THE 2ND HALF OF THE WEEK. 47 TROPICS... NHC IS WATCHING THE WAVE OFF THE YUCATAN COAST AND CURRENTLY GIVING IT A 60% CHANCE OF DEVELOPMENT. THIS SYSTEM WILL MOST LIKELY NOT AFFECT SE TX WX AND PROBABLY BE A MEXICO ISSUE. 47 MARINE... CONVECTION SLATED TO INCREASE/MOVE INTO THE AREA TODAY AS THE WEAK TROPICAL WAVE EDGES CLOSER. THIS SYSTEM WILL ALSO HELP TO SLIGHTLY INCREASE WINDS OVER THE COASTAL WATERS AND HAVE ISSUED SMALL CRAFT EXERCISE CAUTION FLAGS FOR THIS AFTN. THESE FLAGS MIGHT NEED TO BE EXTENDED INTO TONIGHT. THESE STRONGER EASTERLY WINDS MAY ALSO HAVE IMPACTS ON LOCAL TIDES (WHICH ARE CURRENTLY RUNNING ABOUT 1-1.5 FT ABOVE NORMAL). 41 AVIATION... PER SHORT-RANGE MODELS WE SHOULD HAVE A VERY DISTINCT LINE OF HAVE AND HAVE NOTS WITH RESPECT TO PCPN. THE BOUNDARY LOOKS TO BE RIGHT ALONG I-10. AS SUCH NO REAL ARGUMENTS WITH THE GOING TAF SET UP OF KEEPING THE MENTION OF VCTS PRIMARILY SOUTH OF HOU. WILL HAVE SOME ISSUES WITH SUN NIGHT/OVERNIGHT INTO MON WITH THE RE-START OF PCPN AS THE WEAK TROPICAL WAVE CONTINUES TO AFFECT OUR WX. 41 SMOKE... ERLY TRANSPORT WINDS WILL CONTINUE TO BRING SOME SMOKE INTO THE HOUSTON/GALVESTON & SURROUNDING AREAS FROM AN ONGOING WILDFIRE IN SOUTHERN JEFFERSON COUNTY (NEAR CLAM LAKE). HOPEFULLY THIS FIRE WILL ENCOUNTER SOME RAINFALL TODAY AND LESSEN IMPACTS. BUT...YES...THAT`S WHAT MANY OF US ARE SEEING AND SMELLING THIS MORNING. 47 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 75 94 74 96 75 / 20 30 10 20 10 HOUSTON (IAH) 75 90 75 95 75 / 30 40 20 30 10 GALVESTON (GLS) 79 88 80 91 81 / 60 60 30 40 20 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL 10 PM CDT THIS EVENING FOR THE FOLLOWING ZONES: MATAGORDA BAY...WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL 20 NM TO 60 NM... WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM... WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM. && $$ AVIATION/MARINE...23
AREA FORECAST DISCUSSION
NWS SPOKANE WA
237 PM PDT Sun Aug 25 2013 .SYNOPSIS... The moist southwest flow the region has been in over the past week or so will once again bring the chance for showers and thunderstorms this afternoon into the overnight hours. As we move into the work week precipitation chances will diminish with only the higher terrain having a decent chance for activity. Another weather system over the weekend will raise chances for widespread precipitation once again. && .DISCUSSION... Tonight through Monday evening: The big picture includes a large ridge of high pressure centered near Missouri and a large trof of low pressure over the northeast Pacific. The semi-permanent trof has been providing the Pacific Northwest with a busy pattern...namely disturbances rotating around the base and bringing enhanced chances of precipitation to the region. The most recent upper level wave is evident on water vapor satellite imagery moving inland near the California/Oregon coast. Clouds are streaming ahead of this system throughout the inland northwest. More importantly showers and thunderstorms are developing over Oregon that will migrate toward the inland northwest this evening. Overnight convection: isolated to scattered thunderstorms (some severe this afternoon) in Oregon will eventually morph into a large rain shield with embedded thunderstorms as it moves into central and eastern Washington. The concern with our thermal profile is the potential for a gust front along and ahead of the line of storms. The latest runs of the HRRR support this with a large band of rain and possible gust front heading north across the state late this evening through the late night hours. We have increased our chances of precipitation with this feature as well as added wording about the potential for gusty winds. With each run of the HRRR, the speeds of the storms are increasing so will have to monitor close this evening and update as necessary. Still some weak elevated instability remains on the back side of the wave so a few showers still possible overnight. Monday: Weather pattern quiets down for most of the region as the next wave approaches Monday. The majority of the energy associated with this wave will affect the northwest part of the state leaving the inland northwest under partly cloudy skies with just a few showers and thunderstorms possible in the afternoon and evening. The exception will be near the Cascade crest where scattered showers and isolated thunderstorms will again develop in the afternoon and evening hours. The relatively quick storm motion with these storms as well as tonights activity will minimize the threat of flooding. Precipitable water values remain 120-180% of normal for this time of the year so what isolated activity does develop will be wet...minimizing the potential for dry lightning strikes. /AB Monday Night through Thursday Evening...The Inland Northwest will be sandwiched between the trough of low pressure moving south toward along the BC coast and a hefty ridge of high pressure anchored over the central portion of the country. The tug-of-war will be pulled to the slightly retrograding ridge for Tuesday and especially Wednesday, and the temperature forecast shows this with readings 5 to 8 degrees above normal by midweek. After that, a disturbance rounding the trough will begin the breakdown of the ridge for our region, and opening the door for the weekend system to follow on its heels. Cooling temperatures closer to normal Thursday also look likely as a front traverses eastern Washington and the Idaho panhandle. As far as precipitation goes, the Cascades should remain under the influence of the trough and any minor shortwave that moves over western Washington Tuesday and Wednesday. Precipitation chances were not changed much from previous forecasts, which keeps slight chances along and just east of the crest. Farther east, there may be a few showers/thunderstorms that move north in the monsoonal flow, although these chances look to be highest south and east of the ID panhandle. As the shortwave on Thursday moves east, slightly higher chances will exist over mainly the higher terrain, although some of the precipitation may move into the valleys. ty Thursday Night through Saturday Night: Starting the period we will be in the never ending SW flow that will continue to bring chances of showers and t-storms mainly in the higher elevations. The system will send a final frontal wave through Friday afternoon into the overnight that will bring a good chance for rain and thunderstorms for the Cascades...the NE Mtns of WA and the ID Panhandle. Models are finally showing the persistent trough and associated low pressure system will eject into the region next weekend. Where models lack consistency is the track and exact timing of the system passage. The GFS would bring the system onshore on the Oregon coast whereas the EC would bring it onshore on the Washington coast. Regardless the region will see widespread rain showers and the threat for thunderstorms. Models are showing a pretty good amount of associated moisture with the system and when it reaches the Cascades rain will be expected. With the Cascades expected to receive a fair amount of rain we will have to monitor the area for Hydrology concerns. With the exit of the system comes more uncertainties...the EC quickly exits the system Monday whereas the GFS has the system stall over the region bringing a much more prolonged period of precipitation. With the event still almost a week away we have time to refine the details...but overall next weekend looks to be wet. Concerning other aspects of the forecast...winds look to kick up during the daytime periods but should not bring any problems. Temperatures will be cooling down as our flow shifts to more westerly rather than the southwest flow. As of right now temperatures look to drop back into the 70s and 80s by the weekend. /Fliehman && .AVIATION... 18Z TAFS: Shower activity diminished this morning with VFR and light winds prevailing for all TAF locations. Minor diurnal wind shifts expected late this morning through the early afternoon hours as a more potent short wave approaches the region from the southwest. This wave will bring a renewed threat of showers and thunderstorms overnight. Updated from prob30 to tempo for chances of showers tonight and may have to add a new FM group with later updates to capture the onset of precipitation. Ceiling and visibility generally expected to remain high with the exception of the stronger thunderstorms embedded within tonights activity. /Brown && .PRELIMINARY POINT TEMPS/POPS... Spokane 59 79 58 83 60 88 / 50 20 10 10 10 10 Coeur d`Alene 57 79 55 83 57 88 / 50 20 10 10 10 10 Pullman 51 80 51 85 52 88 / 50 20 10 10 10 10 Lewiston 62 87 62 92 63 95 / 40 20 10 10 10 10 Colville 55 82 53 86 53 91 / 40 20 20 10 10 10 Sandpoint 53 77 50 81 50 86 / 50 20 20 10 10 10 Kellogg 56 78 56 83 56 86 / 50 20 20 10 10 10 Moses Lake 59 82 58 86 59 89 / 30 20 10 10 10 10 Wenatchee 62 81 62 85 64 88 / 40 20 10 10 10 10 Omak 60 82 58 85 59 89 / 30 30 20 10 10 10 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...&& $$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
346 PM CDT SUN AUG 25 2013 .SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT) ISSUED AT 346 PM CDT SUN AUG 25 2013 MAIN FORECAST CONCERNS ARE ON SEVERE THUNDERSTORM POTENTIAL TONIGHT THROUGH TUESDAY AND HEAT INDEX VALUES. LATEST SURFACE OBSERVATIONS PLACED A WARM FRONT EXTENDING FROM SOUTHEAST NORTH DAKOTA THROUGH NORTHERN MINNESOTA...STRETCHING EAST OVER SOUTHERN LAKE SUPERIOR. WATER VAPOR IMAGERY AND RAP 500 MB ANALYSIS SHOWED HIGH PRESSURE CENTERED ALONG THE KANSAS/MISSOURI BORDER WITH A FLATTENING RIDGE EXTENDING NORTH INTO THE UPPER MISSISSIPPI RIVER VALLEY. A FEW SUBTLE SHORTWAVES NOTED...THE FIRST WAS LOCATED OVER THE EASTERN DAKOTAS AND ANOTHER...SLIGHTLY STRONGER WAVE...WAS MOVING INTO EASTERN MONTANA. THE WARM FRONT AND THESE TWO WAVES WILL BE THE MAIN FEATURES TO KEEP A CLOSE EYE ON THROUGH MONDAY MORNING. ALSO...A PLUME OF MONSOONAL MOISTURE WAS STREAMING NORTHWARD THROUGH THE DESERT SOUTHWEST AND INTO WESTERN NEBRASKA/SOUTH DAKOTA...HEADING EAST. THUNDERSTORMS ARE EXPECTED TO DEVELOP ALONG THE WARM FRONT THIS EVENING...THEN MOVE SOUTHWARD OVERNIGHT. IT APPEARS THAT THE STORMS WILL INITIATE OVER EAST CENTRAL MINNESOTA INTO NORTHWEST WISCONSIN THEN SHIFT SOUTHWARD WITH TIME DURING THE OVERNIGHT HOURS POTENTIALLY IMPACTING AREAS NORTH OF INTERSTATE 90. CAPE VALUES ARE RATHER IMPRESSIVE LATE THIS AFTERNOON OVER THESE AREAS...WITH TEMPERATURES IN THE UPPER 90S AND DEWPOINTS IN THE LOWER 70S PRODUCING 3500 TO 4000 J/KG OF SURFACE BASED CAPE. SHEAR ISN/T OVERLY IMPRESSIVE WITH 0-6KM BULK SHEAR VALUES OF AROUND 30 KTS...MAINLY NORTH OF INTERSTATE 94. HOWEVER...THE SHEAR IS FOCUSED IN THE 0-3 KM LAYER WHICH WOULD FAVOR THE POTENTIAL FOR LINEAR STORM STRUCTURES WITH DAMAGING WINDS. THE HIGH INSTABILITY OVER THE AREA SHOULD OVERCOME THE LACK OF STRONG SHEAR...LEADING TO THE POTENTIAL FOR SEVERE THUNDERSTORMS WITH LARGE HAIL AND DAMAGING WINDS. STRONG 850 MB MOISTURE TRANSPORT FOCUSES INTO THE WARM FRONT TONIGHT WHICH COULD POTENTIALLY LEAD TO REPEATED ROUNDS OF THUNDERSTORMS ALONG IT. PRECIPITABLE WATER VALUES INCREASE TO 2.0 TO 2.3 INCHES TONIGHT...WHICH IS AROUND 230 PERCENT OF NORMAL. ALSO...WARM CLOUD DEPTHS INCREASE TO AROUND 4.7 KM. ANY THUNDERSTORMS THAT DEVELOP IN THIS AIRMASS WILL BE VERY EFFICIENT RAIN PRODUCERS. THESE FACTORS COULD LEAD TO FLASH FLOODING OVER PORTIONS OF NORTHERN AND NORTH CENTRAL WISCONSIN TONIGHT INTO EARLY MONDAY MORNING. CONFIDENCE ON SEVERE THUNDERSTORM POTENTIAL IS HIGHEST NORTH AND EAST OF INTERSTATE 94 TONIGHT. A STRONG CAP ALONG AND SOUTH OF THESE AREAS SHOULD LIMIT HOW FAR SOUTH CONVECTION CAN BUILD. CANNOT RULE OUT THE STORMS MAKING IT TO THE INTERSTATE 90 CORRIDOR BUT THEY SHOULD QUICKLY DISSIPATE IF THEY MAKE IT ANY FURTHER SOUTH AND ENCOUNTER THE STRONG CAP. SHOWERS AND STORMS SHOULD QUICKLY TAPER OFF EARLY MONDAY MORNING AS MOISTURE TRANSPORT WEAKENS. DEPENDING ON HOW THE OVERNIGHT CONVECTION PLAYS OUT...THE WARM FRONT LOOKS TO BE ORIENTED JUST NORTH OF THE INTERSTATE 94 CORRIDOR BY LATE MONDAY MORNING INTO MONDAY AFTERNOON. MLCAPE VALUES INCREASE INTO THE 2000 TO 3500 J/KG RANGE ALONG THE FRONT BY MID AFTERNOON ON MONDAY. 0-6 KM BULK SHEAR VALUES HOVER AROUND 30 KTS OVER MUCH OF NORTHERN AND CENTRAL WISCONSIN MONDAY AFTERNOON INTO MONDAY EVENING WHICH WOULD FAVOR SEVERE MULTICELL STORMS. WITH THE HIGH CAPE VALUES NEAR THE WARM FRONT...CANNOT RULE OUT A FEW SUPERCELL STRUCTURES ESPECIALLY OVER NORTHWEST INTO NORTH CENTRAL WISCONSIN. ALSO FORECAST MODELS SUGGEST THERE COULD BE JUST ENOUGH 0-1 KM SHEAR TO SUPPORT AN ISOLATED TORNADO OR TWO NEAR THE WARM FRONT. OTHERWISE...THE STORMS WILL BE CAPABLE OF PRODUCING LARGE HAIL...DAMAGING WINDS...AND HEAVY RAINFALL. THE SHOWERS AND STORMS WILL CONTINUE INTO MONDAY NIGHT WITH THE HIGHEST CHANCES MAINLY ALONG AND NORTHEAST OF INTERSTATE 94. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 346 PM CDT SUN AUG 25 2013 SHOWERS AND STORMS WILL BE ONGOING TUESDAY MORNING...MAINLY ALONG AND EAST OF THE MISSISSIPPI RIVER. A WEAK COLD FRONT IS EXPECTED TO SWEEP ACROSS THE REGION TUESDAY AFTERNOON. A FEW SHOWERS AND STORMS CANNOT BE RULED OUT ALONG THE FRONT TUESDAY AFTERNOON INTO TUESDAY EVENING...BUT IT APPEARS A CAP WILL HOLD STRONG FOR AREAS WEST OF THE MISSISSIPPI RIVER...WITH A CHANCE OF SHOWERS AND STORMS OVER MUCH OF WESTERN INTO CENTRAL WISCONSIN. 925MB TEMPERATURES COOL INTO THE 22 TO 25 C RANGE IN THE WAKE OF THE FRONT. SO WE SHOULD SEE A VERY SMALL RELIEF FROM THE HEAT WITH HEAT INDEX VALUES FALLING INTO THE MID TO UPPER 90S. SURFACE HIGH PRESSURE SETTLES OVERHEAD ON THURSDAY BRINGING SOME SLIGHTLY COOLER AIR WITH IT...WITH 925MB TEMPERATURES FALLING TO AROUND 23 C...PRODUCING HIGHS IN THE UPPER 80S TO AROUND 90. THE HIGH SLIDES OFF TO THE EAST ON FRIDAY AS A WARM FRONT PUSHES EAST OUT OF THE NORTHERN/CENTRAL PLAINS. WEAK SHORTWAVES ARE EXPECTED TO INTERACT WITH THE FRONT BRINGING CHANCES FOR SHOWERS AND STORMS TO THE AREA FROM THURSDAY AFTERNOON THROUGH FRIDAY NIGHT. MODEL SOLUTIONS START TO DIVERGE SATURDAY INTO SUNDAY ON TIMING OF THESE SHORTWAVES SO CONFIDENCE LOW ON PRECIPITATION CHANCES SATURDAY INTO SUNDAY. TEMPERATURES ARE EXPECTED TO WARM SLIGHTLY FOR THE WEEKEND WITH HIGHS CLIMBING INTO THE UPPER 80S TO LOWER 90S...DEPENDING ON TIMING OF THE SHORTWAVES AND ANY SHOWERS AND STORM ASSOCIATED WITH THEM. 850MB TEMPERATURE STANDARDIZED ANOMALIES HOVER AROUND PLUS 2 THIS WEEKEND THROUGH EARLY NEXT WEEK SO WILL HAVE TO KEEP A CLOSE WATCH ON THE POTENTIAL FOR HEAT HEADLINES WITH THE POSSIBILITY OF SEEING NEAR RECORD HEAT FOR THESE DATES. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 1215 PM CDT SUN AUG 25 2013 BREEZY SOUTHWEST WINDS TO CONTINUE THROUGH EARLY THIS EVENING BEFORE SUBSIDING AFTER SUNSET...OTHERWISE VFR CONDITIONS WILL PREVAIL. ATTENTION THEN TURNS TO INCREASING CONFIDENCE OF A THUNDERSTORM COMPLEX DEVELOPING ACROSS CENTRAL MN INTO NORTHWEST WI THIS EVENING...THEN MOVING SOUTHEAST THROUGH THE AREA OVERNIGHT/EARLY MONDAY MORNING. QUESTION WILL BE HOW FAR SOUTH THIS COMPLEX OF STORMS GETS/POTENTIAL OF AFFECTING TAF SITES/ BEFORE SHUNTING EAST MONDAY MORNING. FOR NOW...HAVE CONTINUED A VCTS MENTION AT KRST/KLSE TAF SITES IN THE 09-15Z TIME FRAME. MODEL SOUNDINGS SHOWING THAT THIS CONVECTION/STORMS WILL BE ELEVATED IN NATURE WITH CLOUD BASES GENERALLY AOA 8KFT. LOOKING FOR THIS COMPLEX OF STORMS TO SHIFT EAST OF THE AREA AFTER 15Z WITH VFR CONDITIONS EXPECTED. && .CLIMATE... ISSUED AT 346 PM CDT SUN AUG 25 2013 THE FOLLOWING ARE RECORD HIGHS FOR LA CROSSE AND ROCHESTER THROUGH LABOR DAY WEEKEND...GIVEN THE HEAT FORECAST. FOR MORE CLIMATE INFORMATION...SEE OUR WEBSITE AND THE TOP NEWS STORY ON THE HEAT. LA CROSSE ROCHESTER --------- --------- MON 8/26 96/1991 95/1955 TUE 8/27 95/1973 93/1984 WED 8/28 97/1955 96/1955 THU 8/29 95/1966 92/2012 FRI 8/30 97/2012 96/1941 SAT 8/31 95/1953 93/1960 SUN 9/1 98/1913 94/1937 MON 9/2 98/1937 94/1929 NORMAL HIGH TEMPERATURES THROUGH THIS PERIOD ARE 78-80 AT LA CROSSE AND 76-78 AT ROCHESTER. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR WIZ017-029- 032>034-041>044-053>055-061. MN...HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR MNZ079- 086>088-094>096. IA...HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR IAZ008>011- 018-019-029-030. && $$ SHORT TERM...WETENKAMP LONG TERM...WETENKAMP AVIATION...DAS CLIMATE...WETENKAMP
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1215 PM CDT SUN AUG 25 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 330 AM CDT SUN AUG 25 2013 MAIN FORECAST CONCERNS ARE ON TEMPERATURES TODAY AND THUNDERSTORM POTENTIAL TONIGHT. ...CURRENTLY AS OF 08Z... WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED TROUGHING ALONG THE WEST COAST OF NORTH AMERICA AND STRONG SUBTROPICAL RIDGING ENCOMPASSING KANSAS AND MISSOURI. AROUND THE RIDGING... MONSOONAL MOISTURE AND SHORTWAVES WERE EMANATING FROM BAJA CALIFORNIA / WHERE TROPICAL DEPRESSION IVO WAS LOCATED / NORTH- NORTHEAST INTO THE DAKOTAS. ONE SUCH MONSOONAL SHORTWAVE...ENHANCED BY CONVECTION...WAS TRACKING ACROSS NORTHERN ONTARIO. THE CONVECTION WITH THIS SHORTWAVE EXTENDS SOUTH INTO NORTHERN MN AND UPPER MI...BEING FED WITH MOISTURE BY A 35-50KT 850MB JET SEEN ON VWP AND PROFILER DATA EXTENDING FROM NEBRASKA INTO WESTERN LAKE SUPERIOR. EVEN A FEW STRAY SHOWERS EXTEND SOUTH INTO TREMPEALEAU COUNTY. REGARDING THE MOISTURE...GOES DERIVED PRECIPITABLE WATER IMAGERY SHOWED VALUES OF 1.5-2 INCHES ACROSS MUCH OF THE UPPER MIDWEST. THE CONVECTION IS ALSO RIDING ALONG THE EDGE OF A HOT AIRMASS ENCOMPASSING THE CENTRAL AND NORTHERN PLAINS AS WELL AS THE UPPER MIDWEST. RAP SHOWED 700MB TEMPS OF 12C OR HIGHER FROM DULUTH MN BACK INTO WESTERN NEBRASKA. MEANWHILE...DOWN AT 850MB...READINGS RANGED FROM 20-22C OVER THE FORECAST AREA TO 26-28C IN SOUTH DAKOTA. THE WARM AIRMASS EXTENDS DOWN TO THE SURFACE...WHERE OVER THE FORECAST AREA...A SOUTH BREEZE AND DEWPOINTS IN THE UPPER 60S TO LOW 70S HAS KEPT TEMPS AT OR ABOVE 70F. ALSO OF NOTE AT THE SURFACE IS A LOW PRESSURE TROUGH FROM INTERNATIONAL FALLS MN SOUTHWEST TO PHILLIP SOUTH DAKOTA. ...HAZARDS... 1. HEAT ADVISORY REMAINS ON TRACK FOR TODAY AND IN FACT HEAT INDICES MAY END UP HIGHER. 2. POTENTIAL CONVECTION TONIGHT COULD POSE A SEVERE RISK... PRIMARILY NORTH OF I-90. ISOLATED LARGE HAIL AND DAMAGING WINDS MAIN HAZARDS. ...SYNOPTIC OVERVIEW... 25.00Z MODELS ARE IN VERY GOOD AGREEMENT SHOWING THAT A WEAK 500MB RIDGE AXIS PRESENT ACROSS MN WILL FLATTEN OUT TODAY...THEN REBUILDS OVER THE DAKOTAS AHEAD OF A MORE DYNAMIC SHORTWAVE LIFTING OUT OF ARIZONA INTO WYOMING. WITHIN THE 500MB FLOW...MODELS SUGGEST A MONSOONAL SHORTWAVE SOMEWHERE IN NORTHWEST COLORADO OR EASTERN WYOMING CURRENTLY TO CROSS CENTRAL MN AND NORTHERN WI TONIGHT. ...DETAILS... THE FLATTENING OF THE 500MB FLOW TODAY WILL HELP TO SPREAD MORE OF THE WARMTH SEEN OVER SOUTH DAKOTA EASTWARD. 850MB TEMPS CLIMB TO 21-23C WHILE DOWN AT 925MB THEY JUMP TO 26-28C. MIXING TO THE 850MB TEMPS WHICH SEEMS QUITE REASONABLE GIVEN THAT WE SHOULD HAVE FULL SUN AND A BREEZY SOUTHWEST WIND YIELDS HIGHS IN THE LOW TO MID 90S. NOTICED THAT THE RAP IS EVEN WARMER...SUGGESTING HIGHS OF 95-100. THE REASON IS DUE TO SUPERADIABATIC EFFECTS...WHICH LOOK A BIT OVERDONE. WITH DEWPOINTS HOVERING IN THE UPPER 60S TO LOWER 70S ALL DAY...HEAT INDICES SHOULD TOP OUT BETWEEN 97-102. NOW THE BIGGER QUESTION IS CONVECTION CHANCES FOR LATE THIS AFTERNOON INTO TONIGHT. A COUPLE OF SCENARIOS EXIST... 1. THE 25.00Z NAM QUICKLY ERODES THE CAP BETWEEN 18-21Z FROM DULUTH INTO WESTERN UPPER MI...PERHAPS CAUSED BY AN OUTFLOW BOUNDARY EMANATING FROM CURRENT CONVECTION TRACKING ACROSS LAKE SUPERIOR. THIS CONVECTION THEN DIVES SOUTH INTO NORTHERN SECTIONS OF THE FORECAST AREA DURING THE EVENING INTO THE 850MB MOISTURE TRANSPORT AXIS...FOLLOWING CORFIDI VECTORS. THE CONVECTION EVENTUALLY WANES AFTER MIDNIGHT AS THE CAP RESTRENGTHENS. CONCERNED THAT THE NAM...IN PARTICULAR ITS BMJ CONVECTIVE SCHEME...MAY BE ERODING THE CAP TOO QUICKLY. 2. THE 25.00Z GFS...24.12Z ECMWF...THE BULK OF THE 25.03Z SREF MEMBERS AND 25.00Z HIRES-ARW GENERALLY WAIT TO BREAK OUT CONVECTION UNTIL AFTER 00Z ACROSS CENTRAL MN INTO NORTHERN WI...WHICH THEN DROPS SOUTH MORE INTO THE FORECAST AREA AFTER 06Z. AGAIN THE CONVECTION DIVES INTO THE 850MB MOISTURE TRANSPORT AXIS...FOLLOWING CORFIDI VECTORS. ADDITIONALLY...THESE MODELS SUGGEST THAT SHORTWAVE COMING OUT OF NORTHWEST COLORADO AND EASTERN WYOMING COULD BE AN ENHANCING PLAYER. 3. THE 24.12Z HIRES-ARW...25.00Z CANADIAN...UKMET AND ECMWF HAVE THE ONLY CONVECTION OCCURRING ACROSS NORTHERN WI AND UPPER MI TONIGHT... ON THE NOSE OF THE 850MB MOISTURE TRANSPORT. THEY SUGGESTS THE CAP HOLDS FOR LATE THIS AFTERNOON THROUGH TONIGHT...DIFFERENT FROM EITHER OF THE ABOVE 2 SCENARIOS. WHICH OF THE ABOVE 3 SCENARIOS PANS OUT BASICALLY DEPENDS ON THE STRENGTH OF THE CAP. FOR NOW LEANED TOWARDS SCENARIO NUMBER 2 AS IT HAS THE STRONGEST CONSENSUS...THOUGH CANNOT COMPLETELY RULE OUT NUMBER 3. THEREFORE...HAVE LIMITED PRECIPITATION CHANCES TO NO MORE THAN 50. THE SECOND SCENARIO ALSO POSES A MARGINAL SEVERE RISK NORTH OF I-90...GIVEN 0-6 KM SHEAR VALUES REACHING 25-30 KT AND STRONG INSTABILITY. MULTICELLS SEEM TO BE THE MOST LIKELY STORM MODE. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 330 AM CDT SUN AUG 25 2013 ...HAZARDS... 1. HEAT. HEAT ADVISORIES CONTINUE TO LOOK SOLID FOR MONDAY AND TUESDAY...AND THERE IS EVEN SOME CONCERN WE MAY HAVE TO UPGRADE PORTIONS OF THE AREA TO EXCESSIVE HEAT WARNING ON TUESDAY. THE ADVISORY MAY ALSO HAVE TO BE EXTENDED INTO WEDNESDAY SOUTH OF I-90. ANOTHER ROUND OF HEAT HAZARDS ARE POSSIBLE FOR LABOR DAY WEEKEND. 2. STORMS. POTENTIAL FOR SOME SEVERE WEATHER MONDAY NIGHT IF THE 25.00Z NAM/GFS ARE CORRECT WITH ANOTHER THUNDERSTORM COMPLEX MOVING THROUGH. ISOLATED LARGE HAIL AND DAMAGING WINDS MAIN HAZARDS. ...SYNOPTIC OVERVIEW... THE SUBTROPICAL HIGH CENTERED OVER KANSAS AND MISSOURI REMAINS PROGGED TO RETROGRADE WESTWARD TO SIT MOSTLY OVER KANSAS FOR TUESDAY THROUGH THURSDAY. THIS RETROGRESSION IS CAUSED BY DEEPER TROUGHING GRADUALLY FORMING OVER NEW ENGLAND. WHAT HAS BEEN PROBLEMATIC IS AFTER THURSDAY. 24.12Z ECMWF KEPT A NORTHWEST FLOW PATTERN GOING OVER THE FORECAST AREA FOR FRIDAY AND SATURDAY AS THE TROUGH PERSISTS IN NEW ENGLAND. HOWEVER...THE NEW 25.00Z ECMWF GOES ALONG WITH THE 25.00Z GFS TO ALLOW THE SUBTROPICAL HIGH AND ASSOCIATED RIDGING TO SHIFT EAST QUICKER. THIS MEANS THAT HEAT ISSUES ARE MORE LIKELY FOR LABOR DAY WEEKEND. ...PRECIPITATION DETAILS... ALL INDICATIONS ARE THAT SHOULD CONVECTION FROM TONIGHT SHOULD WEAKEN MONDAY MORNING DUE TO DIMINISHING MOISTURE TRANSPORT. MAINTAINED 20-40 PERCENT CHANCES MAINLY ACROSS WI FOR THE CONVECTION. THESE CHANCES SHIFT TO NORTH OF I-94 FOR THE AFTERNOON WHERE THE REMNANT OUTFLOW/WARM FRONTAL BOUNDARY MAY SERVE AS A TRIGGER FOR RENEWED CONVECTIVE DEVELOPMENT. OF COURSE...SHOULD THE UKMET/CANADIAN/ECMWF PAN OUT...MONDAY WILL BE DRY. 20-40 PERCENT CHANCES CONTINUE MONDAY NIGHT AND TUESDAY...GENERALLY ALONG AND NORTH OF I-94...WHERE ANOTHER THUNDERSTORM COMPLEX MAY SLIDE ACROSS AS INDICATED BY THE 25.00Z NAM/GFS. THESE STORMS WILL ALSO HAVE THAT STRONGER SHORTWAVE LIFTING OUT OF WYOMING AT 12Z MONDAY...HEADING INTO CENTRAL/NORTHERN MN BY 12Z TUESDAY FORCING IT. NOTE THAT THE 25.00Z ECMWF/CANADIAN/UKMET ARE FARTHER NORTH WITH THIS COMPLEX...SO MONDAY NIGHT AND TUESDAY COULD BE DRY AS WELL...THUS THE 20-40 PERCENT CHANCES. SIMILAR TO TONIGHT...SHOULD THE COMPLEX ROLL THROUGH...CANNOT RULE OUT SOME SEVERE WEATHER POTENTIAL WITH THEM. COLD FRONTAL PASSAGE OCCURS TUESDAY NIGHT BUT INDICATIONS ARE THAT THE AIRMASS MAY BE TOO CAPPED TO ALLOW ANY CONVECTION WITH IT. IN FACT MOST MODELS ARE DRY. THEREFORE REDUCED CHANCES SUCH THAT ONLY A 20 PERCENT CHANCE IS LEFT CLOSER TOWARDS CENTRAL WI TO BLEND WITH NEIGHBORING OFFICES. WEDNESDAY STILL LOOKS DRY WITH THE FRONT SOUTH OF THE AREA. SMALL CHANCES OF STORMS RETURN THURSDAY THROUGH FRIDAY AS THE FRONT COMES BACK AS A WARM FRONT. DRY CONDITIONS ARE ANTICIPATED SATURDAY WITH THE AREA IN THE WARM SECTOR. ...TEMPERATURE DETAILS... ON MONDAY...EVEN IF THERE ARE STORMS DISSIPATING IN THE MORNING AND NEW ONES FIRE LATER IN THE DAY...ALL INDICATIONS ARE THAT THERE WILL STILL BE PLENTY OF TIME FOR TEMPERATURES TO RECOVER. 925 AND 850MB TEMPS ARE ABOUT 1C HIGHER COMPARED TO TODAY...THUS ANTICIPATING HIGHS 1-2 F HIGHER. UPPER 60S/LOW 70S DEWPOINTS STILL SEEM REASONABLE RESULTING IN 100-105 HEAT INDICES. TUESDAY STILL LOOKS LIKE THE HOTTEST DAY AS 925-850MB WINDS VEER MORE WESTERLY...REALLY ADVECTING THE CORE OF THE HOT AIR OVER SOUTH DAKOTA AND NEBRASKA AT US. 925MB TEMPS CLIMB TO AROUND 30C OVER MOST OF THE FORECAST AREA WHICH IS USUALLY A GOOD CORRELATION FOR 100F TEMPS. RAISED HIGHS A LITTLE MORE AND FURTHER INCREASES MAY BE REQUIRED. DEWPOINTS LOOK LIKE THEY SHOULD HOLD THROUGH EVAPOTRANSPORATION IN THE UPPER 60S/LOW 70S...WHICH MEANS HEAT INDICES COULD CROSS THE 105 WARNING THRESHOLD IN SOME SPOTS. WEDNESDAY IS BECOMING A BIT MORE CONCERNING AS THE 25.00Z ECMWF/GFS ARE NOT AS QUICK BRINGING IN THE COOLER AIR BEHIND THE COLD FRONT. 925MB TEMPS STILL GET UP TO 28C OR HIGHER. THUS...INCREASED HIGHS A FEW DEGREES TO SHOW UPPER 80S TO LOW 90S. THESE MAY NEED TO BE INCREASED MORE...WHICH WOULD PROMPT AN EXTENSION OF THE HEAT ADVISORY ANOTHER DAY. THURSDAY AND FRIDAY WILL BE THE COOLEST DAYS...RELATIVELY SPEAKING AS 925MB TEMPS ONLY COOL TO 25-27C. THEN IF THE NEW 25.00Z ECMWF AND GFS ARE CORRECT...THESE CLIMB RIGHT BACK UP TO EVEN WARMER THAN THE CURRENT HEAT STRETCH...TO 30-32C FOR SATURDAY AND SUNDAY. IF THIS OCCURS...WE COULD EASILY BE LOOKING AT 100 DEGREE HEAT NEXT WEEKEND. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 1215 PM CDT SUN AUG 25 2013 BREEZY SOUTHWEST WINDS TO CONTINUE THROUGH EARLY THIS EVENING BEFORE SUBSIDING AFTER SUNSET...OTHERWISE VFR CONDITIONS WILL PREVAIL. ATTENTION THEN TURNS TO INCREASING CONFIDENCE OF A THUNDERSTORM COMPLEX DEVELOPING ACROSS CENTRAL MN INTO NORTHWEST WI THIS EVENING...THEN MOVING SOUTHEAST THROUGH THE AREA OVERNIGHT/EARLY MONDAY MORNING. QUESTION WILL BE HOW FAR SOUTH THIS COMPLEX OF STORMS GETS/POTENTIAL OF AFFECTING TAF SITES/ BEFORE SHUNTING EAST MONDAY MORNING. FOR NOW...HAVE CONTINUED A VCTS MENTION AT KRST/KLSE TAF SITES IN THE 09-15Z TIME FRAME. MODEL SOUNDINGS SHOWING THAT THIS CONVECTION/STORMS WILL BE ELEVATED IN NATURE WITH CLOUD BASES GENERALLY AOA 8KFT. LOOKING FOR THIS COMPLEX OF STORMS TO SHIFT EAST OF THE AREA AFTER 15Z WITH VFR CONDITIONS EXPECTED. && .CLIMATE... ISSUED AT 330 AM CDT SUN AUG 25 2013 THE FOLLOWING ARE RECORD HIGHS FOR LA CROSSE AND ROCHESTER THROUGH LABOR DAY WEEKEND...GIVEN THE HEAT FORECAST. FOR MORE CLIMATE INFORMATION...SEE OUR WEBSITE AND THE TOP NEWS STORY ON THE HEAT. LA CROSSE ROCHESTER --------- --------- SUN 8/25 97/1948 97/1948 MON 8/26 96/1991 95/1955 TUE 8/27 95/1973 93/1984 WED 8/28 97/1955 96/1955 THU 8/29 95/1966 92/2012 FRI 8/30 97/2012 96/1941 SAT 8/31 95/1953 93/1960 SUN 9/1 98/1913 94/1937 MON 9/2 98/1937 94/1929 NORMAL HIGH TEMPERATURES THROUGH THIS PERIOD ARE 78-80 AT LA CROSSE AND 76-78 AT ROCHESTER. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR WIZ017-029- 032>034-041>044-053>055-061. MN...HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR MNZ079- 086>088-094>096. IA...HEAT ADVISORY UNTIL MIDNIGHT CDT TUESDAY NIGHT FOR IAZ008>011- 018-019-029-030. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION...DAS CLIMATE...AJ
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1147 AM CDT SUN AUG 25 2013 UPDATED UPDATE/AVIATION PORTION FOR 18Z TAF ISSUANCE .UPDATE... ISSUED AT 1129 AM CDT SUN AUG 25 2013 LATEST MESO ANALYSIS INDICATED THINGS WERE SETTING UP ACROSS NORTHERN WISCONSIN AND UPPER MICHIGAN LATE THIS MORNING. SURFACE BASED CAPES WERE ALREADY BETWEEN 2000 AND 3000 J/KG...DCAPES WERE AT 1000/1500 J/KG AND LIFTED INDICES OF -4 TO -6 C AND 0-6KM SHEAR OF 30 TO 35 KNOTS. ALSO...IMPRESSIVE POOLING OF DEW POINTS AROUND 850MB...ALONG WITH MOISTURE CONVERGENCE NOTED ON THE SPC MESOANALYSIS PAGE. INCREASING LOW LEVEL JET LATER THIS AFTERNOON ALONG WITH ALL THE HEAT AND HUMIDITY WILL PROVIDE AMPLE SUPPORT FOR STRONG TO SEVERE THUNDERSTORM DEVELOPMENT LATE THIS AFTERNOON OR EARLY THIS EVENING ACROSS NORTHERN WISCONSIN. THE STORMS WILL GRADUALLY SAG SOUTHWARD ACROSS THE REMAINDER OF THE AREA DURING THE EVENING INTO EARLY MONDAY MORNING. MODIFIED SOUNDINGS AT RHINELANDER INDICATED 3000 TO 3500 J/KG OF CAPE...WET BULB HEIGHTS NEAR TWELVE THOUSAND FEET AND WINDEX VALUES OF 45 TO 55 KNOTS. DESPITE BEING LATER IN THE EVENING OR EARLY MONDAY MORNING...ENOUGH 0-6 KM SHEAR SUPPORT THE POTENTIAL FOR SOME DAMAGING WINDS OR LARGE HAIL ACROSS THE FOX VALLEY AND LAKESHORE REGION. ALSO...TORRENTIAL RAIN WILL BE ACCOMPANIED BY SOME OF THE STORMS THAT COULD PRODUCE LOCALIZED FLOODING. LOOKING AHEAD TO MONDAY...CONVECTION TONIGHT COULD HAVE A BIG IMPACT ON MAXIMUM TEMPERATURES WHICH IS PROBLEMATIC FOR HEAT HEADLINES. WILL NEED TO ASSESS THIS FOR THE AFTERNOON PACKAGE. .SHORT TERM...TODAY...TONIGHT...AND MONDAY ISSUED AT 500 AM CDT SUN AUG 25 2013 UPPER RIDGE CONTINUES TO FLATTEN OVER THE WESTERN GREAT LAKES AS SHORT WAVE IMPULSE MOVES EAST ACROSS NORTHERN LAKE SUPERIOR THIS MORNING. FOR THE MOST PART...SHORT RANGE MODELS INCLUDING THE HRRR AND RAP DID A RATHER LOUSY JOB HANDLING STRONGER CONVECTION NORTH OF WISCONSIN...AS WELL AS LIGHTER SCATTERED SHOWER ACTIVITY MOVING ACROSS CENTRAL AND NORTHERN WISCONSIN EARLY THIS MORNING. SCATTERED SHOWER AND ISOLATED THUNDERSHOWER ACTIVITY OVER THE FORECAST AREA APPEARS TO BE ASSOCIATED WITH VERY WEAK UPPER-LEVEL IMPULSE...MODEST WAA AND NEAR EASTERN EDGE OF ROBUST CAP EXTENDING FROM CENTRAL MINNESOTA INTO NORTHWEST WISCONSIN. THIS ACTIVITY WILL CONTINUE TO PUSH ACROSS THE FORECAST AREA THIS MORNING AND SHOULD REMAIN SCATTERED AND LIGHT IN INTENSITY. ACTIVITY EXPECTED TO BE EAST OF THE FORECAST AREA BY AROUND 15Z. LOOKING FARTHER UPSTREAM...MORE SCATTERED THUNDERSTORM ACTIVITY HAS DEVELOPED OVER WESTERN MINNESOTA AHEAD OF FRONTAL BOUNDARY OVER THE DAKOTAS. MAJORITY OF THE GUIDANCE SUGGESTS THAT THIS ACTIVITY WILL BEGIN TO SINK MORE SSE ACROSS CENTRAL MINNESOTA LATER THIS MORNING AND GRADUALLY WEAKEN AS IT CONTINUES TO PROPAGATE AWAY FROM FRONTAL BOUNDARY. HOWEVER LATEST RADAR TRENDS SHOWING MORE OF AN EASTWARD MOVEMENT AND IF THIS ACTIVITY HOLDS TOGETHER IT MAY IMPACT THE NORTHWEST PORTION OF THE FORECAST AREA LATE THIS MORNING. WILL NEED TO KEEP AN EYE ON THIS ACTIVITY THIS MORNING. FOR NOW WILL STICK TO CURRENT THINKING THAT THIS ACTIVITY SHOULD WEAKEN BEFORE IT REACHES THE FORECAST AREA. THUS IT APPEARS THAT FORECAST AREA STILL ON TRACK FOR A HOT AND INCREASINGLY HUMID DAY. DID NOT MAKE ANY CHANGES TO PREVIOUS MAX TEMPERATURE FORECAST FOR TODAY THUS STILL EXPECT TEMPS TO REACH THE 90-95 DEGREE RANGE OVER THE WESTERN PORTION OF THE FORECAST AREA WITH READINGS NEAR 90 ACROSS THE NORTH WOODS. DID ADJUST DEW POINTS DOWN A DEGREE OR TWO THIS AFTERNOON WITH ANTICIPATED AFTERNOON MIXING. THUS HEAT INDICES WILL BE GENERALLY IN 95 TO 100 DEGREE RANGE WITH HIGHEST VALUES OVER THE WESTERN PORTION OF THE FORECAST AREA THIS AFTERNOON. FOR THIS EVENING AND TONIGHT...QUESTION THEN BECOMES WHEN AND WHERE THUNDERSTORM ACTIVITY WILL FIRE AS SHORTWAVE IMPULSE HEADS EAST TOWARD THE WESTERN GREAT LAKES AND FRONTAL BOUNDARY APPROACHES. ALTHOUGH THERE HAS BEEN A VARIETY OF SOLUTIONS AS TO HOW THE SCENARIO WILL PLAY OUT...SEEMS THAT A WEAK CONSENSUS OF THE GUIDANCE SUGGESTS THAT THUNDERSTORM ACTIVITY WILL DEVELOP NEAR THE WISCONSIN-MICHIGAN BORDER...ALONG AND AHEAD OF FRONTAL BOUNDARY FORECAST TO DRIFT SSE INTO NORTHERN WISCONSIN THIS EVENING. THIS BOUNDARY MAY ALSO GET SOME REINFORCEMENT FROM LAKE SUPERIOR BREEZE. THIS ACTIVITY SHOULD THEN SAG SOUTHWARD ACROSS THE FORECAST AREA OVERNIGHT INTO MONDAY MORNING. SHOULD BE PLENTY OF INSTABILITY OVER THE FORECAST AREA SUNDAY EVENING WITH MLCAPES AROUND 3000 J/KG. BEST DEEP LAYER SHEAR TO SUSTAIN UPDRAFTS WILL BE OVER THE NORTHERN HALF OF THE FORECAST AREA. SPC ADDED MOST OF THE FORECAST AREA INTO A SLIGHT RISK FOR SEVERE LATE THIS AFTERNOON AND INTO THE LATE EVENING HOURS WHICH SEEMS REASONABLE. PRIMARY THREAT APPEARS TO BE DAMAGING WINDS AND PERHAPS SOME LARGE HAIL. MODELS VARY AS TO THE TIMING THE CONVECTION WILL FIRE...BEST GUESS IS SOMETIME IN THE 23-02Z TIME FRAME WITH ACTIVITY MOVING SOUTH OR SOUTHEAST ACROSS THE FORECAST AREA TOWARD MIDNIGHT. WILL ALSO NEED TO KEEP AN EYE ON A LOCALLY HEAVY RAINFALL THREAT...ESPECIALLY IF ACTIVITY CAN TRAIN FROM WEST TO EAST ALONG FRONTAL BOUNDARY LATER TONIGHT. MORE UNCERTAINTY FOR MONDAY AS MODELS DIVERGE ON HOW LONG ACTIVITY WILL PERSIST ALONG FRONTAL BOUNDARY EXPECTED TO BE LOCATED SOMEWHERE OVER NORTHERN WISCONSIN. LOCATION OF RESIDUAL THUNDERSTORM OUTFLOW IS ALSO A FACTOR AS TO WHERE ADDITIONAL CONVECTION MAY FIRE AGAIN DURING THE DAY ON MONDAY. FOR NOW KEPT BROAD BRUSH CHANCE POPS ACROSS THE ENTIRE FORECAST AREA. MAX TEMPS ON MONDAY WILL BE DEPENDENT ON RESIDUAL CLOUD COVER...PRECIPITATION AND LOCATION OF FRONTAL BOUNDARY. .LONG TERM...MONDAY NIGHT THROUGH SATURDAY ISSUED AT 501 AM CDT SUN AUG 25 2013 WHILE THE CNTRL CONUS UPR RDG TO REMAIN THE MAIN WEATHER FEATURE THRU MUCH OF THE UPCOMING WEEK...ITS SLOW RETROGRESSION FROM THE MID-MS VALLEY TO THE CNTRL HI PLAINS WL ALLOW THE MEAN FLOW TO TURN NW BY THU AND BRING SLIGHTLY COOLER/DRIER CONDITIONS TO NE WI. MAIN FCST EMPHASIS TO BE THRU MID-WEEK AS A FRONTAL BOUNDARY MOVES THRU AN UNSTABLE AIR MASS AND SETS THE STAGE FOR TSTMS. A FEW OF THESE STORMS MAY BECOME STRONG TO SEVERE WITH LOCALLY HEAVY RAINFALL. TEMPS TO REMAIN WELL ABOVE NORMAL TIL FURTHER NOTICE... ESPECIALLY THRU THU. PLENTY OF QUESTIONS LINGER FOR TUE STARTING WITH WHERE (IF) MON NGT`S CONVECTION TO BE LOCATED...WHERE THE NRN WI FRONTAL BOUNDARY TO RESIDE...WL ADDITIONAL PCPN DEVELOP ON THE EDGE OF THE CAP AND COULD ANY OF THESE STORMS TURN SEVERE? THE KEY APPEARS TO BE THE MON NGT CONVECTION SINCE IF IT WERE TO DEVELOP...MORE CLOUDS AND BRIEF STABILIZATION WOULD OCCUR. IF THIS CONVECTION STAYS TO THE NORTH...THIS WOULD ALLOW TEMPS TO SOAR ONCE AGAIN AND ALLOW THE ATMOSPHERE TO REALLY DESTABILIZE BY THE AFTERNOON. TO TOP ALL OF THIS OFF...THE MDLS BRING A WEAK SFC TROF INTO WI. HARD TO FATHOM NOT SEEING ANY PCPN MON NGT...THUS HAVE SIDED WITH MENTIONING A HIGHER POP ON TUE ACROSS FAR NE WI WHERE THE WEAKER CAP WL EXIST. SEVERE POTENTIAL TO BE DICTATED BY HOW WARM WE CAN GET AND WHETHER THAT APPROACHING WEAK SFC TROF CAN GENERATE ENUF LIFT TO BREAK THE CAP. IF THE CAP IS BROKEN...WE COULD SEE A ROUND OF STRONG TO SEVERE STORMS WITH LARGE HAIL...DAMAGING WINDS AND TORRENTIAL DOWNPOURS. SHWR/TSTM THREAT WOULD CARRYOVER INTO TUE EVENING UNTIL THE SFC TROF EXITS THE AREA AND A WEAK AREA OF HI PRES BEGINS TO BUILD ACROSS THE UPR MS VALLEY. ONLY CHANGE TO THIS PART OF THE FCST WAS TO FOCUS PCPN CHCS TO THE EVENING WITH A CLEARING TREND FOR THE OVRNGT HOURS. BY THE MIDDLE OF THE WEEK...THE UPR RDG IS PROGGED TO HAVE RETROGRADED BACK TOWARD THE CNTRL PLAINS WTH THE MEAN FLOW OVER THE GREAT LAKES TURNING MORE NW. WEAK HI PRES TO BE SITUATED OVER THE WRN GREAT LAKES REGION ON WED...THUS A DECENT AMOUNT OF SUNSHINE IS ANTICIPATED. 8H TEMPS TO STILL BE AROUND +20C...SO TEMPS WL REMAIN RATHER WARM WITH A MINOR DROP IN DEW POINTS BEHIND THE DEPARTED SFC TROF. THERE ARE NOW CONCERNS FOR THU`S DRY FCST AS THE MDLS ARE INDICATING THE NEXT MID-LEVEL SHORTWAVE TROF TO BE ROUNDING THE CNTRL CONUS UPR RDG AND DIVING SE TOWARD WI. NOT SURE AT THIS POINT WHETHER THIS POTENTIAL CONVECTION WOULD IMPACT ALL OF NE WI OR DIVE SE ENUF TO ONLY AFFECT CNTRL WI. AT THIS POINT...FOLLOWED THE CONSENSUS SOLUTION WHICH BRINGS A SLIGHT CHC POP TO MUCH OF THE FCST AREA. TEMPS FOR WED LOOK TO BE SIMILAR TO WED WITH PLENTY OF 80S TO GO AROUND. ANOTHER AREA OF HI PRES IS EXPECTED TO BUILD SWD FROM CANADA DURING THE THU NGT/FRI TIME PERIOD. DO NOT CARE FOR THE MINIMAL POP ADVERTISED BY THE CONSENSUS SOLUTION AND PREFER TO GO DRY FOR FRI WITH TEMPS GENERALLY IN THE 80-85 DEG RANGE. RETURN FLOW THEN SETS UP OVER THE REGION NEXT WEEKEND WHICH WL LEAD TO WARMER TEMPS...AN UPTICK IN HUMIDITY LEVELS AND THE POSSIBILITY OF WAA- INDUCED PCPN CHCS. ATTM...ANY PCPN APPEARS TO BE WIDELY SCT AT BEST WITH NO FOCUSING MECHANISM PRESENT. && .AVIATION...FOR 18Z TAF ISSUANCE ISSUED AT 1127 AM CDT SUN AUG 25 2013 STRONG TO SEVERE THUNDERSTORMS ARE EXPECTED TO DEVELOP ACROSS NORTH-CENTRAL WISCONSIN LATE THIS AFTERNOON OR EARLY THIS EVENING... THEN SAG SOUTHWARD ACROSS THE AREA DURING THE EVENING INTO EARLY MONDAY MORNING. SOME OF THE STRONGER STORMS COULD PRODUCE GUSTS OVER 50 KNOTS AND HAIL OVER 1 INCH IN DIAMETER. 12Z TAFS SEEMED TO HAVE A PRETTY GOOD HANDLE ON TIMING OF CONVECTION AND WILL MAKE SOME MINOR ADJUSTMENTS THERE. GREATEST RISK OF SEVERE WEATHER SHOULD BE NORTH AND WEST OF THE FOX VALLEY. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE.........ECKBERG SHORT TERM.....ESB LONG TERM......KALLAS AVIATION.......ECKBERG